British Agusta A109 specialist Castle Air currently has two more examples of "the best production helicopter in the world" passing through its maintenance facility. The machines, a A109A-II and a A109E, will be available for sale in due course.

The firm, based in Liskeard, Cornwall, claims to be one of the biggest Agusta service centres in Europe.

It flies around 1,200 hours with its own A109 charter fleet, as well as undertaking photography and filming flights for well-known British television shows along Cornwall's picturesque coast.

Castle Air's sales director Ross Bunyard, says: "We've been trading for 27 years. In the last five to six years we've moved heavily into the selling of A109s.

"The twin turbine market is really buoyant now. It's really worldwide demand for the aircraft that's fuelling it. People are starting to realise that helicopters are cost-effective business tools. And the economy is very buoyant in the UK at the moment, which obviously helps.

"Why twins? They're great vip machines. If you have to get four to six people somewhere in quick time, the A109 is a great machine. It's the fastest production helicopter in the world."

He says that Castle Air enjoys a great relationship with Agusta, and carries a "huge" amount of parts for the aircraft.

"When we get these aircraft, we do a full survey, make sure the aircraft is 100 per cent. We can paint-strip the aircraft back to metal, re-paint it to the buyer's specifications, do the interior, and we have a massive amount of used and new parts, so we bring the aircraft up to certain Castle Air standard."

The firm also operates one JetRanger, which it uses as a filming aircraft on BBC television shows including Top Gear and Coast.

"We try and stick to what we know," says Bunyard. "For main-tenance, you've got to understand these machines inside and out; if you spread yourself too thin, then you're asking for trouble."