Having tracked down all seven of the eight remaining City of London police telephone posts, I decided to turn my attention outwards towards the rest of London. By the late 1930s, the Metropolitan Police had erected almost seven hundred police boxes and around seventy of the smaller posts so surely some of those must remain in place?
Police Call Posts
Metropolitan Police Heritage Centre
We’ll start with police call posts, which — being smaller and thus less of an obstruction — are more likely to have survived. Even so, the prognosis isn’t great. Unlike the City, where the governing Corporation is inclined to restore the discarded call posts of its police force, such relics in Greater London are at the mercy of various different London Boroughs. They can’t really count on much love from the Met either, which abandoned them decades ago.
And, having said that, let’s immediately belie it with this:

The police call post above is, of course, non-functional. And though it appears to be an original, it’s not in its original place. The building above is the police station in Lillie Road in West Brompton in the Royal Borough of Kensington & Chelsea. Not coincidentally, the building is also home to the Met’s heritage centre (i.e. a museum) and shop.
The installation of the police post was quite recent (it’s not in Google Streetview from 2012, for instance) but as it’s basically a museum exhibit, it nicely demonstrates what one should look like if intact…

It’s a darker blue than the sky blue of the City and, since these posts were put up in several different boroughs, it eschews borough emblems in favour of a royal crown and the initials ‘MP’ (for Metropolitan Police). The lamp at the top is white.
Piccadilly Circus
So, having found one newly installed, can we find an actual original? I was pretty sure I remembered seeing one at Piccadilly Circus and, sure enough, there one was. Spot the difference:

At first sight you might think that the City of Westminster has not been taking care of its street furniture. The borough that maintains a multitude of working gas lamps has let this police post get a bit battered. The instruction sign is missing but that makes sense — it’s probably best not to confuse tourists into thinking it’s still in use. And most bizarrely, the royal crown has gone missing. How is that even possible?
The answer is that it isn’t an original Met police post. There was one on the exact same spot but someone dug it up and stole it during the late 1980s. Westminster City Council could have just paved over the hole and dismissed it with a shrug but instead they sought a replacement. The post in the photo is actually a City of London post, repainted dark blue and its red lantern swapped out with clear glass. The letters MP have been added where the post once bore the City’s arms but I guess a crown was too difficult or expensive or something. It does have to be said, though, that they’ve not looked after it since.
Grovesnor Square

The phone post above is in Grosvenor Square, also in the City of Westminster. It stands in the square itself, facing the embassy of the country which dreamt up the idea. The US embassy has occupied its site on Grosvenor Square since 1938 but plans to move out next year when their new purpose-built building is completed in Nine Elms in Wandsworth. The driving reason for the move is said to be security concerns rather than a fit of pique at the call post’s ruinous state.
Northwood Police Station
The only other police call post in London, so far as I know, is way out down the Metropolitan Line in Northwood. It stands, rather pointlessly, in the grounds of Northwood Police Station with a modern phone beside it just to rub in its obsolescence.

Police Boxes
Trafalgar Square
So, that’s police posts wrapped up. What about actual police boxes? Did any of those survive? Well sort of. There is only one original police box in situ in London, and that one was always a bit special.

Today, Trafalgar Square police box is basically a broom cupboard, used by the City of Westminster to store cleaning equipment and the like. It was carefully blended with Trafalgar Square’s architecture so as to not be an eyesore — this is a TARDIS whose chameleon circuit still works. The lantern on top is often mistakenly said to come from HMS Victory, which it sadly doesn’t. It does predate the police box though.
Covent Garden
Not too far away, in Covent Garden, another police box has followed suit, finding new life as a storage shed. It probably graced a street corner somewhere for decades but now huddles away from the crowds in the churchyard of St Paul’s Church.

This wooden booth is a much older design than the 1928 ‘TARDIS’ version. It probably dates to the mid 1890s and would have been purely for police use — no public call phone was installed.
In fact, at first, it probably lacked any phone at all, being just a hut to rest in during inclement weather; telephones were added to booths like these in 1905. With no lamp to summon a policeman, it relied on the ringing of the telephone or a red disc shown in the window by an arm that dropped down when the phone rang.
Earl’s Court
And, finally, there’s this:

The Earl’s Court ‘watchbox’ was installed in 1996, a collaboration between the Metropolitan Police and London Underground. It is basically a mini police station and CCTV monitoring hut — in addition to feeds from various other cameras, the ‘lamp’ on the top is a camera mount— and clearly takes its design cues from the 1928 standardised police box. But, despite what it says at the top, it has never been a public police call box.
The Met apparently planned to build more of these but ultimately decided not to. It probably didn’t help that in 1998 they found themselves in a trademark wrangle with the BBC:
In 1994, Auntie Beeb had taken advantage of a revision of trademark law to register the blue police box as a trademark. This would hardly have seemed unreasonable at the time, given that there hadn’t been an actual working police box on London’s streets for nearly thirty years and anyone seeing one would almost certainly associate it with Doctor Who. This meant, though, that anyone using the police box image needed to licence it from the BBC.
In 1998, the Met, who had discovered this with some sense of rising incredulity, challenged it in court. Their position was simple: It was the Met who actually designed that iconic image and they were still using it. I mean, look at Earl’s Court!
The court was not swayed. Yes, the image was theirs when associated with police work but not as a merchandising image. No one, absolutely no one, shown a police box would respond with anything other than “that’s the TARDIS”. The court decided in favour of the BBC, fined the Met £850 for trademark infringement and made them pay the BBC’s costs. If only they’d had a time machine…