Some people collect matchboxes, coins or postcards. Others find military vehicles float their boat. Meet one of Norfolk's keenest collectors of Jeeps, tanks and armoured cars.

It all began when retired farmer Brian Mack went to an auction in Harrogate, North Yorkshire, to buy a motorbike and something else caught his eye.

He came home with a Second World War army lorry instead - and a serious dose of the military collecting bug.

'I saw a Fordson WOT2 truck in desert trim, I remembered seeing them go by when I was a child in the war,' said Mr Mack, 76, who grew up and began his farming career at Barroway Drove, near Downham Market. 'A wave of nostalgia hit me, so I bid on it - and won.

'Since then I've gradually built up my collection and joined the Norfolk Military Vehicle Group, attending shows and rallies to raise money for charity. I've enjoyed every minute, but maintaining the collection is a lot of work and I'm not getting any younger.'

For now the barns at Rookery Farm, near Denver Sluice, are crammed with 1930s, 40s and 50s Jeeps, cars, trucks and a pair of giant Centurion tanks, which have followed the first Fordson bought in 2001.

Mr Mack said he gave up farming his land -which stretches away from Sluice Road to the banks of the Cut-Off Channel - 20 years ago. He said modern farming methods have become so advanced since he last grew spuds or sugar beet, he wouldn't know where to start.

'They're still runners,' he said as 'Barney' (aka Roger Barnard), the army-trained mechanic who comes in one day a week to help maintain the collection, fires up one of the Centurions' huge 12-cylinder engines, making the barn shake.

'We've put a new clutch in one of them. We go off-roading and take them round the fields, they do four gallons a mile - that's £25 a mile,' he said.

The collection also includes a rare six-wheeler Saladin armoured car, a Green Goddess fire engine and a REME mobile workshop complete with lathe and benches housed in a heavyweight lorry. When asked, he says he doesn't have a clue what it's all cost him over the years.

Mr Mack still drives some of cars to take part in shows and enthusiasts' events organised by the 100-strong Norfolk Military Vehicle Group. He has also staged shows on his 150-acre farm, raising thousands for King's Lynn-based forces' family charity Scotty's Little Soldiers.

So will he feel a tinge of sadness to see his beloved collection go under the hammer, when the auction gets under way on October 4?

'I was an agricultural dealer, So I've always bought and sold,' he said. 'Once they're sold they're crossed off. Twenty's too many, there's always something going wrong with one of them. Cheffins the auctioneers say they've had no end of interest.'

Jeremy Curzon, from Cheffins, said: 'There are some fabulous vehicles in Brian's collection, including the most aggressive looking Volvo in the world – a 1954 all-terrain command vehicle – and a fully equipped Royal Engineers mobile workshop from the 1960s.

'Along with a few vintage tractors, trailers and trucks, we hope to start the auction with the boom of a 25-pounder field gun – another of the lots on offer – instead of the traditional sound of the auctioneer's bell.'

Mr Mack admits he might hold on to a car or two or perhaps a Jeep.

If you want to snap up a Saladin or a Centurion, the sale is being held on Saturday, October 4. For more details, click here.