The unique level of excitement and gusto associated with the height of Group B rally racing might feasibly not be seen again in top-tier motorsport.

For what the class offered in drama and sheer spectacle, it was equally fraught with controversy as the hitherto unseen levels of supercar performance on special stages brought a lingering sense of danger for both drivers and racegoers.

The formula existed for just four years, though its impact on both the sport and the wider consciousness was disproportionate to its relatively short time in the public eye.

The Delta S4 was Lancia’s proposed solution to the earlier 037 having taken just one win from the 1984 World Rally Championship.

By the mid-1980s, the 037 was not an old car but its architecture pegged Lancia behind contemporary rival manufacturers, with its race entrant still built around two-wheel-drive technology.

The Delta S4 was introduced for the last race of the 1985 season with an ingenious “twin-charging” system, whereby a...