The angels who have long smiled on Robbie Williams' bulging bank balance appear to have finally flown the nest – because I can reveal the pop superstar has been left nursing a jaw-dropping £11.9million loss on a Swiss mansion he bought from a golfing pal. Robbie, 52, splashed £26.6million on the sprawling estate in the ultra-exclusive village of Vandoeuvres, near Geneva, in December 2020, buying it from wealthy businessman Nicolas Brunschwig. The pair sealed the deal over a round on the fairways at the prestigious Golf Club de Geneve – reportedly without lawyers or estate agents. Despite drawing up plans to transform the property with a…