Bonhams is selling the bikes plus 10 cars and assorted automobilia from the Exmoor Classic Car Museum at its Beaulieu sale in Hampshire on Saturday, September 8.

The Phebus, a 2¾hp motor tricycle frame, is expected to fetch between £30,000 and £35,000, while other choice lots include a 1947 Dot 122cc AA tri-car and a 1956 BMW 494cc R50 & Steib 250S sidecar.

The Exmoor museum, which was based in Porlock, Somerset, was the retirement project of collector Stephen Johns, an entrepreneur who ran a pyjama manufacturing business in Keighley, West Yorkshire for 45 years.

He moved to the West Country 12 years ago and set up the museum to house his personal collection.

Tim Schofield, director of the Bonhams motor car department, said: “The Exmoor Classic Car Museum could be described as every motoring enthusiast’s dream. Museums like it don’t really tend to exist today. When you walked through the doors it was like walking into some forgotten past.

“Today everything is locked away behind glass cabinets, but in this museum the public could touch the cars, open their doors and look inside, and flick through the old photo albums.

“It will be a great shame to see it close, but Bonhams wishes Mr Johns the very best for his ‘second retirement’.”

Among the cars for sale are a 1972 Ferrari 246GTS ‘Dino’ Spider (estimate £100,000-£120,000) and a 1927 Bugatti Type 40 Tourer (estimate £80,000-£100,000).

The full list of 13 Exmoor Classic Car Museum motorcycles for sale:

• 1898 Phebus 2¾hp Motor Tricycle Frame, estimate £30,000-£35,000

• 1969 Velocette 192cc LE, estimate: £2400-£2800

•1981 Triumph 744cc T140V, ‘Royal Wedding’ Bonneville, estimate £3000-£4000

•1971 Bridgestone 345cc GTO, estimate: £1800-£2200

• Circa 1969 Bridgestone 100TMX, estimate: £1000-£1400

• The only known example, 1947 Dot 122cc AA tri-car, estimate: £3000-£4000

• 2009 MV Agusta 998cc F4 1000RR 312, estimate: £6500-£8500

• Circa 1945 BSA 591cc M21 Motorcycle Combination, estimate: £3000-£4000

•Circac.1952 BSA 123cc Bantam D1 'GPO', estimate: £1400-£1800

•1968 BSA 172cc Bantam D10, estimate: £1400-£1800

•1960 BSA 123cc Bantam D1, estimate: £1200-£1600

•1971 BSA 172cc D175 Bantam, estimate: £1200-£1600

•1956 BMW 494cc R50 & Steib 250S sidecar, estimate: £7000-£10,000