Some of the smaller, but still glamorous venues, such as the Royal Court, the Donmar Warehouse and the Almeida, invariably have their after-parties on the premises, so the event is really just a continuation of the interval with finger food.
Leaving the Cottesloe the other night after Detroit, for instance, I noted that one or two tables in the cramped foyer were laid out with buffet nosh for those who felt entitled to stay; the decision seems to be yours entirely.
The same sort of thing happens at Hampstead Theatre these days, where critics are made to feel welcome to hang about, deadlines permitting, with the first night throng, and it's invariably useful to catch up briefly with colleagues, agents, publishers and even actors. Hostilities are temporarily suspended in the no-man's land between seeing the show and departing to write the review.
The West End producers usually throw their after-parties away from the scene of the crime. So, last night's bash after the opening of What the Butler Saw in the Vaudeville was along the Strand at the Waldorf Hilton in the Aldwych, in the big handsome ballroom where they used to hold tea dances until very recently.
The place is so vast you can make your own space, proceed at your own tempo and talk to whoever you like. There are no rules, and no etiquette, and none of the terrible anxiety that surrounds such occasions in New York, where a party in the Tavern on the Green in Central Park, or in Sardi's Restaurant in the middle of the theatre district, is likely to disperse in a silent few minutes if a critical thumbs down is signalled by the New York Times.
Last night, with my friend and neighbour Sarah Coop, who works for the arts organisation Artichoke, I enjoyed time with Whatsonstage.com colleague Theo Bosanquet; Joe Orton's sister, Leonie, who is still fiercely keeping the flame; Nick Bromley, one of the West End's legendary company managers who is about to publish a book of his memories and anecdotes; and the actor Neal Pearson, who tells me that he is researching the late, great Peter Cook's voluminous and so far un-catalogued stash of papers and scripts in his Hampstead house.
Pearson appeared in the 1984 West End production of Orton's Loot alongside Leonard Rossiter as Truscott of the Yard. The design frippery of that revival included the decking out of the theatre foyer in black silk and mourning paraphernalia, which was gorgeously and ironically unfortunate as Rossiter dropped dead in his dressing room half way through a performance.
The same sort of fate can befall a critic. Charles Landstone of the Jewish Chronicle was leaving a performance of Whose Life Is It, Anyway? when he dropped dead in the Strand. That play was in the Savoy, where we re-assemble this evening for the revival of Neil Simon's The Sunshine Boys. I think I'll wear dark glasses in the vain hope that the after-party whisks us all away to a tanning salon.
Anything to cheer us up in this damp and chilly start to the summer. It's nearly time to report back to the Open Air Theatre in Regent's Park, and I dread to think what will happen to the first nighters' picnic plans if the temperatures don't start shifting upwards very soon. Instead of Pimms and smoked salmon, they'll be packing double doses of hot chocolate and Mulligatawny soup.