The dress code was simple: wear what you like. No ties, jacket not essential. You choose. And we all did.
Fortunately, a blend of position, reputation and tariff meant that those who did brave one of the coldest Friday nights of the year didn't let the side down.
And so it was a mix: we had the dinner suit lot on their way to a do, the smart casuals showing that you can get away with jeans if you have the figure for it, and the designer diners giving their blonde dates a Paul Smith cuff or two to hold on to.
I guess it's the sort of crowd you'd want if you're running a small hotel in a posh Thameside town, with its own French-style bistro boasting separate red and white wine stores.
And this was a pretty typical crowd, according to one dressed-to-be-seen couple in the corner of the delightfully dark and comfy pre-dinner-drinks area they call the snug. Also, so I was assured, a regular haunt for many of the non-residents that outnumbered we guests for dinner that night.
Not that I cared. I had a river-view suite to return to: a split-level one with its own terrace that overlooks a maze of red-tiled roofs to the Regatta Lawns.
It even had its own open-air tub for those balmy summer evenings when the only way to unwind is a soak under the stars. Well, given the opportunity…
The three-seater Chesterfield in what was essentially a bathroom was a nice touch, as was the TV you can watch from the bath, the espresso machine and the selection of current-issue magazines in both rooms.
Back to the bistro; very du Vin with its dark leather, polished wooden floors and busy, art-laden walls. You're led into it via a smart bar, again all zinc-topped and French. It's not a place I'd naturally see as a draw for young families but it catered effortlessly for the few there on the night; the pre-teen girls toasting grandad's birthday, the nearly newborn in its buggy, and the terror tot of a two-year-old who chirruped his way between drinkers and diners as staff side-stepped him and occasionally guided him on his way lest he strayed too far.
When the table was ready and the tot wasn't, the waiter simply made one up next to a sofa in the snug. Job done.
The hotel's position is as central as you get without taking to the river, in a side street yards from the Thames and a few oars' lengths away from the shopping streets. The town itself is bookshop-twee and art gallery-indulgent, a place to stroll and unwind without the car.
Which is just as well, as they whisk it away from you when you pull up in the courtyard drop-off area and pop it underground till you need it again.
Rates From £145 per night
Tel: 0845 365 4438