After reading the list of New York restaurant codes, I decided to compile a list of my own, mostly from personal experience (no names mentioned). Here's the London version:
P.H. - Pisshead. Will never leave.
R.P.H. - Rich pisshead. Tear top half off wine list before giving him it.
S.P.H. - Scottish pisshead - handle with care
F/U - Fat or unchic, seat at rear of room.
FUBAR - Fat or unchic beyond all recognition. Refuse table.
M.L. - Mother in Law. 50+ female hell bent on complaining from the start. You can't win.
Merchant Banker - Wanker. Known complainer.
Chimney sweep - American in the room. Put on rubbish cockney accent and skip over pulling on braces for extra tip.
S.P.M. - small plate mug - customer who always over orders on the small plates. Encourage.
Pidge (pigeon) - Ordinary customer. Not big spenders. Don't make any effort, there's thousands of them.
The pigeons are shitting all over the shop - Ordinary customers taking up all the tables, not spending.
Soho duckling - customers in a queue waiting at a no res place
The ducklings are quacking! Throw 'em some bread! - a grumpy queue, give them some nibbles.
Quentins & Lucys - Well-off young people from West London, over in East London, desperate to be cool. Sting em.
Fleas on the dog - People at the table who are obviously not paying.
Bumpkin - Out of towner / someone obviously 'not from round here'.
Bumpkin Billionaire - A shabbily dressed customer, who spends a fortune.
Westfield Winos - Groups of slightly Essexy post-shopping women. Pull out that case of Lambrusco and send out the best looking waiter.
T.T. - Terry Towellings - Group of chavvy shouty blokes. Show expensive steak menu only and declare draught beer off, only exp bottled beer or wine available.
F.B. - Food bloggers. Photo taking tossers. Flirt with their partners outrageously to the point of embarrassing them. Hopefully they won't return.
S.S. - Stuffed shirt. Rich guy, trying to impress. Allow him to, by guiding him to that special bottle of Chateau d'Yquem you have 'saved' for him.
S.S. taking the bait - Rich guy, 2-3 pricey bottles down. Dust off that vintage Cognac menu, quick!