Ruth Parasol and family
Rank 2017

Californian-born Parasol, 50, and her ex-husband Russ DeLeon, 51, were co-founders of PartyGaming, an online casino software pioneer. It floated in 2005, with the pair picking up at least £620m in the following years, and later merged in 2011 with Austrian rival Bwin in a £2bn deal. They sold their final stake for £46m in June 2015 just months before Bwin.Party was taken over by GVC for £1.1bn. Parasol is based in Gibraltar where last year she completed development of a penthouse and office building in John Mackintosh Square. The Parasol Foundation Trust donated £35,000 in 2016 to Cambridge University Women’s Boat Club after identifying it as a “centre of excellence and female empowerment”. She has other interests in finance and property.