Let’s Do The Maths

Look back to when I joined the police are you’ll see that crime levels, measured either by police recorded crime or by the British Crime Survey, were much higher – but if you look at statistics on use of s136 of the Mental Health Act, the quality of them has not always been great, but what we do know, is they’ve mainly just increased year on year, from the first proper attempt at detailed stats in 2007, by the IPCC (as they were then called).

  • 2007 = 18,500 detentions under s136, of which 65% were removed to custody.
  • 2017 = 28,271 detentions* under s136, of which 3.5% were removed to custody.

* we know this figure was too low: Devon and Cornwall Police were unable to submit a return and they have historically reported approximately 1,400 to 1,500 uses of the power per year; and we know some forces under-reported their figures, so it’s likely to be at least 30,000.

It will be the autumn of 2018 before we learn the new figures for 2017/18, but it strikes me we’re due to see another rise, potentially this time a touch steeper than before. And remember: these figures are rising despite the fact that in some areas, street triage has been attributed as reducing the use of s136 quite significantly. In Leicestershire and Northumbria Police areas, for example, they each used to use the power over 800 times a year and now are seeing just high double figures or low triple figures pre year (see image, above) with almost no-one going to custody. Between those two forces alone, they’ve reduced the use of s136 by almost 1,500 but we’re still seeing an overall national increase.  If you’ve checked Twitter today, you’ll see, in just one division of Lancashire Police, they currently have police officers in A&E departments with three separate people detained under s136 and they have been there for fourteen hours, according to their Assistant Chief Constable who has tweeted about this. Just as I responded to him on social media, he mentioned that a fourth person has now been detained and there is still no available Place of Safety in a mental health unit. So that is another person heading to A&E, without specifically needing the services of an A&E department who, no doubt, are fairly stretched themselves with other demand.  This is one police division only: Lancashire have three and there are other s136 detentions in the other divisions at the same time as this.

Now, to make a point that will be uncomfortable, but which I can’t avoid making: we’ve been pushing for years to ensure that we don’t take people to police custody, other than exceptionally. This is right for all manner of reasons which are well rehearsed elsewhere, including by me. But one thing we shouldn’t forget, is that by not removing people to police stations we will increase the amount of police resource necessary to facilitate the process, unless the NHS sets up its place of safety process to comply with nationally agreed standards. And being frank: they often don’t.  I recently reviewed a s136 policy in a force area and it stated “it’s best practice for officers to remain”.  This is actually the opposite of best practice, according to the senior signatories of every relevant organisation in the country.  A vested interest, perhaps? – well, if your Chief Constable can be persuaded to do this for you, you don’t really have to staff your place of safety at all, do you?!  You can the revenue funding it would take to employ a number of nurses or nursing assistants.


When I first joined, someone removed to police custody as a Place of Safety could often be handed over to the staff in the custody office and my partner and I would be back out on the street within an hour, maximum. Occasionally, one of us would have to remain in custody to do ‘constant obs’ or a camera watch and the other would be back out on the street, single-crewed for other work. Those enhanced level of observations may be necessary just until the doctor arrived to authorise a different approach, or it may last until the end of the s136 process, which would last ten and a half hours, on average.

If you open an NHS alternative, the assessment time is often reported as being a five or six hour process and unless the officers are able to leave within one hour – as agreed to be the national standard on s136 in the 2011 RCPsych publication – then that means two officers remaining there. Ten to twelve hours of resource every time, just to get to the assessment. For those 20% of people who would require hospital care, which then means finding a bed and finalising admission arrangements, it would be longer still.

So you can do the maths –

  • Police custody = 10.5hrs per detainee and many of those would not require detaining officers to remain involved; those which do would only require one officer.
  • NHS PoS = 5hrs per detainee, sometimes 6hrs per detainee and then further time for 20% of those and this time two officers would be required.
  • If a force had 500 detentions per year, that might roughly mean* around 2,800hrs per year to handle people via custody and 5,800hrs a year to handle people via the NHS process.

* The mathematics on this is rough and for illustrative purposes only: forces don’t always keep statistics, but it’s predicated on timescales suggested above and where 25% of those detained would require enhanced obs throughout; 25% would require nothing after booking in; and 50% enhanced obs for just the first 4hrs only. In the NHS setting the maths is done on 5hrs to assessment and 20% of those detained for a further 4hrs beyond that for bed search and conveyance. In reality, it’s often way more than that.

Another way of saying all this is: a Chief Constable with 500 detentions per year, who has most of those detentions managed in an NHS Place of Safety which does not or cannot allow the officers to leave after an hour, is putting (roughly and almost) twice as much resource in to that same demand as they were before. It equates to more than one full-time equivalent police officer spent to ‘improve’ things. It may improve the s136 process that someone was not removed to custody, but what does it cost in terms of 999 response, attention to detail in pre-trial disclosure; youth crime prevention work, etc.?  The answer is that it costs something – it’s not cost-free.


Given the success, mentioned above, of street triage in some areas, why don’t forces just do that to help alleviate at least some of this problem? It’s a fair question, but again you probably need to do some maths to understand what’s going on and, again, I’ve covered this before on here. But in summary, depending on which model of street triage you adopt, the Chief Constable could be expending more resource via triage to manage the same demand as before, whilst also encouraging new demand. This argument will not be true of all schemes because there are thee or four ‘models’ of things that we now refer to as street triage, but some schemes are more resource intensive for the police than others – indeed some don’t involve police resources.

If a police area’s Place of Safety process for those detained under s136 involves a 5hr assessment period, followed by further time for those c20% who require admission, we can again work out the hours spent managing that demand. 500 detentions per year means 5,800hrs if we assume that those admitted to hospital will require a further 8hrs of resource after assessment – two officers for 4hrs. If you avoid 90% of those detentions because of street triage, you are now spending roughly 1,300hrs on the 10% and and managing that 90% in a new way. It will still take at least some time to do this and you’ll have to work out what they do instead – suffice to say it may take an hour or so, which seems to be preferable to the 10hrs in the Place of Safety. if we suggest it will still take 1hrs per job after street triage arrive, that’s 450hrs: 1,750hrs spend managing the demand that used to take 5,800 – seems like a saving, doesn’t it?! Used to spend 5,800hrs, now spending 1,750 so roughly a saving of 4,000hrs which is, more or less, two full-time equivalent police officers. Happy days!

But in order to make that possible, you have to maintain a team of police officers: some forces have four, others have six, in order to make the street triage process possible. Those officers work for 2,000hrs a year each – you can then see your 4,000hrs of saving per 500 detentions in that light. If you’ve reduced by 700 detentions per year you may well have saved 5,600hrs, but if it cost you over 8,000hrs to do that, you can’t legitimately claim to have saved two full-time equivalent police officers because you’ve actually spent one, not saved two. But remember: not all street triage schemes are quite as resource intensive but claim success, albeit perhaps not quite so spectacular and not all areas who’ve tried triage in the same way have the same impact. And what this post is not going to explore at all, is the very real phenomenon that the existence of street triage causes dysfunctional behaviour in both policing and in the NHS. << Not just my opinion: this has been said to me again and again and again by both nurses and officers who work on it. That’s a post for another time.


You can’t put a cost on human dignity and the quality of someone’s experience; these figures are back of the envelope numbers to suggest that somebody who can really do maths and good quality research looks at this more closely. HMIC reported in their PEEL Inspections that evaluations of street triage are limited, which follows on from NICE stating that evaluations were ‘poor’ or ‘very poor’. You can argue with my maths if you want, but please don’t write in because I’m not trying to make a precise assessment: just a illustrative point that the ‘solutions’ we keep coming up with to the problems we think we’ve got might be more resource intensive for the police, not less.

And remember, whether or not you like Theresa May or agree with her: the original idea behind making sure that people could access NHS facilities and services for assessment without being detained by the police or without being detained in police custody was about saving police time. We all know, in the real world, it is about more than that – it is about the public we serve: their dignity and wellbeing, their safety and security. But what I’m arguing that we cannot ignore is now a broader discussion about how delivery of the things intended to save time are actually costing us.

There is a resourcing and economic reality to what we do: if Lancashire police currently have eight police officers off the road in A&E departments – two officers for each of the four people detained under s136 – it shouldn’t be much of a surprise if someone who reports anti-social behaviour, or volume crimes in progress finds there is, at best, a delay or at worst, a complete inability to respond. We all want what’s best but I’ve said it before: I’ve been the duty inspector who had to decide whether to order officers out of A&E department and take a risk OR resource some incoming 999 calls which all involved the words ‘shooting’, ‘gun’ or ‘rape’. Quite an invidious position to be placed in, if anything goes wrong with any of those jobs.

I know this risks ‘perpetuating tensions’ and I was reluctant to write this and bang on about it.  But if this tension is not highlighted and discussed, then it merely means a different tension sits with my frontline police officer colleagues who I know have their ongoing versions of the ‘shooting’, ‘gun’ and ‘rape’ dilemmas that I’ve had in the past.  It’s only because this goes precisely against what we all agreed we’d do in 2011 that I feel obliged and entitled to raise it, even if it does ‘perpetuate tensions’.  The tension is already there and it’s not worsening because solutions are more resource intensive than problems and that has to be wrong if it’s because nationally agreed standards aren’t being applied.

Winner of the President’s Medal,
the Royal College of Psychiatrists.

Winner of the Mind Digital Media Award


All views expressed are my own – they do not represent the views of any organisation.
(c) Michael Brown, 2019

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One thought on “Let’s Do The Maths

  1. and lets be clear, just because a PoS is in an NHS hospital and staffed by NHS staff doesn’t make it a better experience for the patient.

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