So his favourite restaurant is Woodruffs Organic Cafe in Stroud, Gloucestershire, which claims to be the country's first 100 per cent organic eatery: "I like organic stuff but I'm also a bit of a fussy eater and they can cater for me.
"I'm a vegan and I recently gave up eating wheat after not eating any while I was in Kyoto for the climate conference. I'm feeling much better for it."
Whether for a mid-morning snack of honey and porridge, made with organic oats and soya milk, or lunch of a Thai curry or Italian fennel bake, he says he doesn't have to pay more than pounds 5 at Woodruffs but "you certainly get full up".
The people who run the cafe are "enthusiastic about what they do and the cooking is fantastic".
Vince, 37, is not keen on doing business in London, though having recently signed a deal with Thames Water, worth pounds 50m a year, he finds himself having to visit the capital about twice a month.
He prefers conducting business in Stroud, where he is based, and says he would have no hesitation about taking business associates for lunch at Woodruffs. But he adds: "It's not as pleasant as doing the job. I prefer to get down to the issues. You can do too much wining and dining."
Woodruffs, 24 High Street, Stroud, Glos (01453 762250)