McNally is also a multi- millionaire who got his first leg- up in business making components for slot machines operated by the Kray twins - he swears he didn't know who they were for - and went on to invent the steel alloy wheel and puncture-proof tyre. His latest gadget, an automatic roulette machine, goes on sale in this country shortly. Another McNally device, a computerised car park, is being built on three sites and he has plans to develop a low-budget, high-performance sports car.
He employs 30 people here and 150 in the US through his company, McNally Industries. The roulette machines and components for the car parks will be made at a new factory being built with government support in Mansfield.
His car parks, he says, are the future. 'Greedy planners want more office blocks. Normally, they can only provide parking for three or four cars. But I can supply parking for 30 or 40 cars in the same amount of space.'
He uses a working model in his kitchen to show how computerised lifts park the cars automatically. When the owner returns, it can retrieve the car from five floors up in less than 40 seconds.
If the system breaks down - and four computers ensure it shouldn't - McNally says he will lay on a limousine to take you where you want to go.
One car park is being erected at Heathrow airport and two more are going up in central London. 'Think about it. If you're building a block of 20 apartments, nobody will give you planning permission unless you can provide parking for 20 cars. This can do that in hardly any space at all.'
And, he claims, his car park - assembled like a giant Meccano set - costs pounds 5,000 per parking space for a minimum of 10 cars, compared with pounds 12,000-15,000 for German and Japanese versions, which only start at 50-60 cars. 'Theirs are much more expensive and you have to be a rocket scientist to maintain them. This beats the hell out of the Japanese and Germans.'
Behind him, a photo of John Major beams down approvingly.