Some will object to the Ritz as wildly extravagant and beyond the firm’s budget (if you are entertaining valuable clients). While £52 for the set lunch is not a small sum, it would be difficult to find anywhere of quality in central London where you could expect to pay much less. And the point about the Ritz is that you would be offering someone a lunch of the very highest quality in one of the finest dining rooms in the world.

One important point to note, especially now that dress-down is so widely observed during the summer months in even the classiest of firms, is that men will need a tie to be served here. This need not be an obstacle so long as you are wearing a jacket. The maître d’ will produce a selection of ties if you or your guest present yourselves without one. This happened the first time I took one particular client, who had come up with his wife to see the Summer Exhibition. Being a bohemian type (there is a surprising amount of artistic endeavour in the making of video games; certainly a lot of copyright, and if we as lawyers are lucky, a certain amount of infringement) my client arrived for the exhibition in a vibrantly coloured jacket, but tieless. The problem was solved expertly by the maître d’ providing an equally colourful tie for the duration of the lunch.

Indeed, it would have been for longer as my client forgot to return it as we were leaving. Luckily, he remembered as soon as we got to the street.

The second crucial rule to follow at the Ritz is: stick to the set menu. The food is outstandingly good, so there is enough choice for even the most demanding of palettes and you will get a number of small appetisers from the chef in addition to your three-course order. But going off piste to the à la carte choices will seriously endanger your wallet.

The set menu changes with the seasons and the produce available. When we went there was a choice of: wild sea trout, terrine of goose liver, and egg and asparagus as starters; halibut, veal or duck for the main course; and apricot soufflé (a must) or coconut mousse for pudding.

A further pointer to ensure you come away satisfied: ask for a window or corner table when you book. This will allow you to scrutinise the room for interesting fellow diners. Apart from clients you would like to act for, you will see the occasional familiar face from Question Time. Lady Thatcher used to come once a week in her retirement.

Also, on both environmental and economic grounds, ask for good London tap water. If you are there on purely professional business you will be financially assisted by the current fashion to avoid alcohol at lunch.

One final ‘tip’ (no pun intended). The bill will already have service included so you don’t need to add anything extra, unless your waiter has been particularly helpful.

Christopher Rees had a 40-year career as a solicitor with Freshfields, Bird & Bird, Herbert Smith and Taylor Wessing