DJ Taylor: Who exactly pays for Rupert St John's expensive, old-fashioned kind of bachelor life?

How does 37-year-old Rupert St John pass a specimen day?

Well, a leisurely breakfast in the Barbican flat might begin at 11.30am, to be followed by a trip "into town" to borrow another Anthony Powell novel from the London Library, a late lunch somewhere in the West End, a snooze in one of the three gentlemen's clubs of which he is a life member, a saunter along the Burlington Arcade, and then dinner with friends. It is a nice, smart, expensive, old-fashioned kind of bachelor life, varied by three holidays a year (Aspen in the spring, South of France in the summer, Scotland in October), whose only mystery, to those newly acquainted with the beneficiary, is who exactly pays for it all?

The answer is Rupert's Uncle Hector, a former industrialist who, upon his death 10 years ago, was discovered to have left his favourite nephew £2m in bonds and gilt-edged stock. On receipt of this largesse, Rupert, at this time a junior manager at the accountancy firm of Tender & Mainprice, gave up his job on the spot, moved out of the flat off the Fulham Road that he had been sharing with three friends, and set up as a full-time gentleman of leisure.

The only problem with an income of £100,000 – the annual return on Rupert's prudently invested windfall – is that, while being enough to allow you not to work, it is insufficient to enable you to do anything serious with it.

Just now, for example, after an unsatisfactory couple of years backing an art gallery, Rupert is the sleeping partner in an antiquarian-book firm, a subject about which he knows a little, but not enough to make his occasional interventions more than a source of annoyance to its principal.

The same feeling of desultoriness hangs over his romantic life. Every so often a girl will fall hook, line and sinker for Rupert's charm, flat and income – only gracefully, or not so gracefully, to recede once she takes the measure of his colossal indolence, self-satisfaction and faint air of detachment from the processes of ordinary life. There is also the fact that, over-lunched and under-exercised, he is rather going to seed.

Still, there is always a trip to Ascot or an evening at Stamford Bridge to raise his spirits, before the limitations of a life lived solely for pleasure come back to haunt him.