The full extent of a bitter row between the Commons watchdog and the speaker has come out into the open.

A series of letters between the pair - published by the speaker Michael Martin - accused Elizabeth Filkin of failing to prove allegations of a whispering campaign against her.

He claimed her documents "identify no names and do not provide the evidence which your allegations would lead one to expect".

In one of the letters, Filkin quotes a former Labour chief whip who advised her to "watch out" in the wake of her investigations into complaints about high profile MPs.

Filkin refused to offer names to avoid breaching confidences but quoted the late Lord Cocks who told her: "You should look after yourself, you need to watch out ... A lot of stuff is going to hit the fan soon."