Complex sentence: Both the above special editions were created by Rob Darcus of Star Custom vehicles, who began developing special trim versions of standard models to help sell more vehicles when he was District Manager for Vauxhall in London.
Split into simpler sentences: Both the above special editions were created by Rob Darcus of Star Custom vehicles. Rob started to develop special trim versions of standard models to help sell more vehicles when he was District Manager for Vauxhall in London.