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But he said he jumped at the chance to continue looking after a world-class motorcycle collection when offered a job by the collection's new owners, Scott and Jocelyn O'Donnell.
''I was approached by Scott, asking if I was in or out. I said 'I'm in'. Just like that.
''I was prepared to do whatever I had to do to go with the bikes. I was prepared to go wherever they went, whether that was overseas or in New Zealand.''
Fortunately, his partner, Jinny, had required no persuading to move to Invercargill with him, he said.
The collection of almost 300 machines ranges from a 1902 Peugeot to a 2007 Simms Corbin Custom and includes brands such as AJS, Ariel, BSA, BMW, Brough Superior, Harley-Davidson, Indian, Matchless, Rudge, Schwinn, and Zundapp.
Rare John Britten bikes on loan through Mr Roberts' connections will also be on display, along with motorcycle-themed art works.
The collection was built up by Nelson businessman Tom Sturgess and in recent years opened to the public.
Mr Roberts (63), who has owned, raced and maintained bikes all his adult life, ran his own plumbing business in Nelson for many years.
He said Mr Sturgess ''hunted him down'' to help with the collection, first as a volunteer and more recently as the paid curator.
''I'd been working for Kevin Grant, who lives in Auckland and owns a Britten, and looking after race bikes for Bruce Verdon, from TT Industries. I'd been to the Isle of Man [races] looking after his bikes. So I'd always had a major interest, and it really was only a matter of time before I hooked up with [Tom].''
He said he was ''realistic'' when Mr Sturgess, who has cancer, told him he intended to sell the collection, but always hoped he could continue his involvement.
Mr Roberts said his first trip to Invercargill was about 1973 or 1974.
''I went to Dunedin for a race but it was called off, so Gary Goodfellow and I came to Invercargill for a drive and visited [motorcycling legend] Burt Munro at his place.
''It wasn't until about 30 years later, in the early days of the Burt Munro Challenge, that I came back with Bruce and raced at Teretonga.''
Classic Motorcycle Mecca will open in two renovated adjoining buildings in Invercargill's CBD on November 22, just before this year's Burt Munro Challenge.
Mr Roberts said he was impressed with the way the O'Donnells, who also operate Bill Richardson Transport World, had renovated the buildings and organised the bike displays.
He said 90% of the bikes in the collection ran and it was possible start-up days might be organised.
''I could probably start 100 of them within four hours. That's what museums do overseas.''