London - Apparently the donor is notorious for his awesome deposits the bulk of which are held on seven day call at the First Coalition Sperm Bank of Westmonster.
This morning Nick Clegg said he'd done nothing wrong after getting caught feasting with the mystery depositor at Mayfair's plush Poison Ivy restaurant last week.
No 10 later commented that Clegg's dinner guest 'was not that Russian ex-banker German Whassisname Gorbuntsov', currently languishing under armed guard at an intensive care ward somewhere in London.
A bar bill seen by QM-NewsCorpse sauces shows the Deputy PM and his anonymous guest drank their way through the restaurant's Fine Whine menu as if fearing an imminent reintroduction of Prohibition.
The next day GlibDem party coffers swelled as Clegg was seen treading his way gingerly to work.
Current estimates of the party's overdraft suggest an awful lot more of this type of donation will be needed in the months to come.