It is a real shame that the previous two reviewers didn't get a chance to try the cocktails here, as they are without doubt, fabulous (sorry, but did you book Pearl by any chance? Same name, different spelling, easy to do, not Purl's fault?).
To be fair to them, the booking process is a bit haphazard; I called to book, was told it was probably ok but somebody would get back to me. They didn't, so I called back. It was all fine, but nobody bothered to tell me. When I called on the day to bring the booking forward an hour, there was no problem, but when we arrived, we were sat on high stools at a former bench-turned-bar in a corridor. Fortunately, our attentive waitress was able to find us a table with the minimum of fuss. In fact, service all round was very good – from the friendly, clip-board wielding door guard at the top of the stairs, to our Hibs supporting, Scottish waitress.
The space itself is really odd: it feels like it wants to be Milk & Honey, all dark, sophisticated and mysterious, but is stuck in a space that is a series of small rooms, interconnected by corridors, where random tables are set. There are two nice alcoves (the old coal holes, under the street) and a big room, which housed a large group. The level of the music, however, is such that you have to be intimate with your drinking companion, as sitting more than a few inches apart makes conversation difficult. The potency of the cocktails ensures that such conversation is fluid.
The cocktail list is short, but interesting. No whatever-the-latest-take-on-a-flavoured-martini-is here. No, the closest that the list comes to mainstream is a Hemingway Daiquiri, which is served with a potently laced marischino. There is a martini, the KetelN2, but this bubbles and spits nitrogen, as it stirred in a nitrogen bath, so that it is served at -50 degrees. Whilst Heston would be proud, it is suggested to guests that they don't start drinking until the bubbles have subsided. Surely nowhere else produces a martini that you have to wait until it warms up before you can drink it. Of a similar theatrical nature, Mr Hyde's Fixer Upper is a dark rum based drink, that is borne to the table in a cooler spewing dry ice, in the middle of which is a flask of rum and smoke! Not quite as dramatic, but the highlight for us, is the Street Urchin: this is a delicate bourbon and pear conconction, that comes in a medicine bottle, which is wrapped in a brown paper bag. no glass; you drink directly from the bottle. The last drink we had, before needing sustenance, was the Backward Bellini, with the fruit (pomegranite, rather than the more usual peach) as a foam on top of the proseco, rather than at the bottom of the glass. Hence backward.
At this point, we did need food, and this is where there is a problem. Most bars will offer something to nibble on. After all, these are highly charged drinks, and something to soak the alcohol up is generally a good thing, especially if you want to sell more alcohol. Purl doesn't offer anything, although the waitress let us have some olives. To be fair, we also saw a takeaway pizza disappear down towards to the large group, but we left to get something to eat. Maybe this will work well, but given that bookings are for an unlimited time (unless somebody is squeezed in before a later booking), and it seems difficult to get in without a booking, if people use this as a pre- or post- dinner place only, surely they are missing a trick. It doesn't need to be much, just something that will make people linger for another cocktail or two, or even move on to the (again short, but well priced) wine list.
As for the cost, well £8-10 for the astonishing cocktails is, in this part of town, excellent value: nearby there are bars at some of the big hotels (Ten Manchester Street, HUNter486 at the Arch, Claridges and the Connaught, for instance), all of which have excellent cocktails (and nibbles). None of them are in the same league as the cocktails mixed at Purl, and all of them will be nearer to twice the price, once the discretionary service charge they all have (and Purl doesn't) has been included.