But despite Watson's not-so-small fortune, he doesn't make New Zealand's top 10 richlisters.
The British-based former Lion Nathan head Sir Douglas Myers remains the wealthiest Kiwi on the list. His estimated fortune has increased £42 million to £429 million.
Banker David Richwhite, who turned 64 on Sunday, gained £26 million to £389 million and took 228th spot on the list.
He passes the Queen, whose fortune is measured at £310 million.
Alan Gibbs, who led the privatisation and restructuring of Telecom NZ and helped set up Sky TV, ranks alongside X Factor creator Simon Cowell and is estimated to be worth £225 million; Sir Colin Giltrap has lifted his fortune to £118 million.
The combined wealth of the 1000 richest men and women in Britain has risen to record levels in the past year, despite the economic slump.
Their total fortune has grown by just under 5 per cent to £414 billion.
Heading the list for the seventh year running is the steel tycoon Lakshmi Mittal, although his wealth has fallen £4.8 billion to £12.7 billion, placing him just £385 million aheadof Alisher Usmanov, whose Metalloinvest is Russia's biggest iron ore producer.
Third-placed Roman Abramovich, owner of soccer club Chelsea, has fallen £800 million to £9.5 billion.
The richest woman is Staffordshire-born former Miss UK Kirsty Bertarelli, who shares a £7.4 billion fortune with her husband, pharmaceutical magnate Ernesto, founder of the Alinghi yachting syndicate.