Nick Newlife placed £1,520 on Federer to win seven Wimbledon singles' titles at odds of 66/1 back in 2003 - the year the Swiss master won his first title - but the 59-year-old from Oxford then died in February 2009.
However, Newlife, who died as a bachelor, made arrangements so that the money would go to Oxfam if the bet ever came off.
"Federer has returned to top form in recent tournaments, losing only to Rafael Nadal in last week's French Open and he is a leading contender for this year's tournament," explained William Hill spokesperson Graham Sharpe.
"Nadal is 2/1 favourite, but Federer is 5/2 second favourite and he could yet prove a literal dead cert for Mr Newlife and Oxfam."
In total Oxfam will receive £101,840 if Federer goes on and wins the title.
They will also have a few more chances to win the money even if he fails, as the bet states that Federer has until 2019 to win his seventh title.
Stuart Fowkes of Oxfam said: "Legacies amount to 10 per cent of our total income from individuals, so they're essential to us, and as this case proves they can come in all shapes and sizes."
- Roger Federer
- Rafael Nadal