He has just returned from a sunsoaked holiday in Barbados where he scorched his forehead on the first day (serves him right, you might think) and it won't be long before he jets off to his house in Bordeaux in the summer to indulge his passion for wines.
But it has been a bumpy few years for the 39-year-old financier. In 1990, his wife divorced him. Lady Rose Cecil, the daughter of the Marquis of Salisbury still crops up in the gossip columns with her ex mentioned in passing. 'I've progressed from being referred to as Mark Flawn Thomas, merchant banker, to Mark Flawn Thomas, investment expert,' he says.
Flawn Thomas is a force in Britain's broker bonds market, a field often regarded with scepticism by financial regulators. Broker bonds allow financial advisers to switch clients' money between the various insurance funds available under a unit-linked life insurance bond. The trouble is, investors have to pay two sets of charges, one to the broker and another to the insurance company. But Flawn Thomas seems to be doing better than most. Since buying Chartfield off an old friend of his father in 1987, funds under management have grown to pounds 60m and, he claims, the figure is doubling every nine months.
'I think getting to a fund of pounds 500m could be relatively easy,' he says. 'The difficulty has been getting to this stage, because you need to establish credibility.'
His pedigree would have helped. He spent four years at Price Waterhouse, then a further four in the investment division of Samuel Montagu, before joining Baring Brothers.
It was at Samuel Montagu that the wine buff, who founded a wine society at Exeter University and later won the Evening Standard wine-tasting competition, got to show off his love of the grape in a bet with Lord Stevens. During the oil stock boom the nobleman financier came on to the floor.
'Everyone was petrified of him,' Flawn Thomas recalls. 'I'd only just been given some funds to manage and he came up to me and said 'I hope you've got enough oil stocks in your portfolio'.
'I said I had but then piped up like an idiot and said 'but of course what we should be investing in is wine'. He looked at me and said, 'right you pick a wine and I'll choose an oil stock'. He chose Lasmo which I think increased by 50 per cent over the year. I chose a rather good red wine, which more than doubled.'