He had various manual jobs, working largely as a tyre fitter before setting up a business at the age of 18 to dismantle old buses and sell their engines to the Far East for use in fishing boats.
In the 1997 general election he selectively funded Eurosceptic Conservative candidates, and in 1998 pledged to "use every means possible" to persuade British voters to say no in a referendum on the single currency, saying he would "raise hellfire to get the message across".
The following year he began making large donations to the cross-party Democracy Movement, founded by Lady Annabel Goldsmith as a successor to the Referendum Party.
Sykes was a vehement opponent of the European Union and is noted for his belief that it represents an undemocratic, bureaucratic, super state in the making.
After treatment for the disease at Johns Hopkins, Baltimore in 2000, he funded the construction of a specialist prostate cancer unit at St James's University Hospital, Leeds.
He funded Sir Ranulph Fiennes' expeditions on the Eiger for the British Heart Foundation, as well as the Everest Challenge and Marathon des Sables for Marie Curie Cancer Care raising millions for the charity.
Sykes now spends most of his time on environmental issues including work with Durrell wildlife conservation trust which is an international body dealing with endangered species.