In such circumstances I can generally manage an hour on one pint and without needing a loo break, although there can be a fair amount of drink-nursing towards the end if people are running late. And books are good because people to whom they're an appealing target are, on balance, more likely to be too wel-brought-up to nab them.
And this is all solo, of course - if there are three people, then the sociability of a (quarter-hour) fag break is still no excuse for not leaving one or two people at the table.

Back then, the Dairy was still a real dairy. I bet the drinks choice was better too.