Mercedes have been producing an SL ( Sport Leicht ) model or range of models since 1954, when the landmark 300SL was unveiled.

The similarly styled, but mechanically unrelated, 190 followed in 1955, completing the first generation of cars.

The second generation SL (W113) began with the 230 of 1963.

It was distinguished by its lower waistline, big curved screens and a distinctive optional hardtop that earned the nickname of "Pagoda top." The larger, third-generation model (R107) was launched in 1971.

The newcomer featured a two-door monocoque bodyshell with independent suspension all round.

Over its very successful 19-year production span the R107 featured no less than two straight-six engines and six V8 units.

The 420SL variant is understood to be the rarest of all the 237,287 R107 SLs made, with just 2,148 leaving the factory between 1985 and 1989.

Its 4.2-litre V8 produced some 215bhp at 5200rpm – sufficient output to endow the big Benz with effortless acceleration and a top s...