"the exclusive London business clubs"

The Athenaeum Club on Pall Mall
Creative Commons Attribution Share AlikeThe Athenaeum Club on Pall Mall - Credit: David Iliff
This probably refers to the gentlemen’s clubs of London, for which Pall Mall in particular is famous. Some of the more well-known clubs on Pall Mall include the Athenaeum, the Travellers Club and the Oxford and Cambridge Club.

Gentlemen’s clubs were private members-only clubs set up by upper class men in eighteenth-century Britain; however, in the nineteenth and twentieth centuries they became popular amongst the middle classes who could afford to pay for membership. In the late 1800s there were around 400 clubs in London, some of which catered to particular political, cultural or sporting interests, others which were based on previous membership to a certain school or battalion of the armed forces. The clubs were not for entertainment purposes – this came later, when many strip clubs took on the name – but were a second home for their members, who may have lived out of town or even abroad. Clubs offered living rooms, a restaurant, games rooms and sometimes bedrooms, allowing their members to socialise, relax, eat and use the building as a base on their business trips to London.

A full list of London’s gentlemen’s clubs, including those no longer in operation or fictional, can be found here.