London Assembly member, Damian Hockney, has defected to Kilroy-Silk's new party, Veritas. Mr Hockney is expected to be appointed deputy leader of Veritas.
UKIP have called on Mr Hockney to resign his seat on the assembly, claiming he had a 'moral obligation' to step aside and let another candidate from the party stand for the assembly.
A UKIP spokesman said that in 2003, Mr Hockney had proposed a motion, passed by the party's National Executive Committee, requiring any successful UKIP election candidate who later left the party to resign their seat.
'UKIP asserts that Mr Hockney has a moral obligation, if not a legal one, to adhere to a rule which he himself was a vocal advocate of,' said the spokesman.
'UKIP has been surprised at Mr Hockney's selective memory in respect of this motion for some time. However, his reported appointment as deputy leader of Veritas explains this failure.'
Two UKIP staff members have followed in Hockney's steps.
UKIP members have dubbed the project Vanitas and warned that, "the future's bright, the future's orange" under the well-tanned Mr Kilroy-Silk.
A spokesman for UKIP said: "Vanitas clearly does not have anything different to offer the public other than an opportunity to swoon at Kilroy-Silk's feet.
"We apologise to the voters who elected a UKIP MEP and ended up with a personality cult."
Source: The Guardian, Wednesday 2 February 2005
Birmingham Post, Wednsday 2 February 2005