Nick Clegg was involved in a bad-tempered clash with Liberal Democrat activists over so-called secret courts legislation and benefits changes tonight.
The Deputy Prime Minister was accused of abandoning the party's values during a question and answer session.
Activists challenged Mr Clegg over the Justice and Security Bill, which would allow courts to sit in secret in some civil cases, with one Lib Dem member questioning why he had "abandoned the high ground" by engaging with the proposals.
Another said: "How can we call ourselves a Liberal Democratic party any more if we vote for this legislation?"
However, the party leader said the intelligence services were currently unable to defend themselves in some civil court cases because they could not disclose sensitive material. He also stressed that many changes had already been made to the original proposals.
But it was clear from his reception that Vince remains immensely popular - the man many see as the only true Lib Dem voice in the Cabinet.
Nick Clegg admitted tonight that his party had let people down, by not properly investigating allegations of sexual harassment.