They may be required to under the rules. I don't know about huge lotteries, but some contests require you to agree to publicity if you win.
(And I adore the word "scrote." Brits have the BEST insults).
Camelot, who run the UK lottery (and the UK involvement in the Euromillions draw) are not allowed to disclose the identity of players or winners without their consent.
The word "scrote" was invented in the 1980s by the writers of the long running TV series "The Bill". The "Old Bill" or just "the Bill" is what many Cockneys call the Metropolitan Police. The series aimed at a "realistic" unglamorous documentary style approach, and they aimed to get the police dialogue, accents, etc as accurate and true to life as possible. They did a lot of research into how real police officers talk, (their language is very rich in slang)* but they soon ran into a problem, which is that real police officers swear a lot. Since the show was going out before the watershed they were forced to mostly cut that right down, but they wanted a word that the officers could use for describing despised criminals, so they invented "scrote". It seems to be passing into the language.
*
Not many Uncle, this slag's got a slimy on the Bill."
Detective Constable serving in the Metropolitan Police Service [allegedly] explaining to a judge that a witness gave false evidence out of malice.http://www.urbandictionary.com/define.php?term=police%20slang&page=4When someone runs away Met cops may well say he "had it away on his toes", and men used to be (probably still are) arrested in public toilets for something they call a "crosshand boogie".