The DPP and the legal blonde he called to the bar

Sir Ken Macdonald, a married father of three, is revealed to have had clandestine meetings with Kirsty Brimelow, 37, a barrister and Criminal Bar Association spokeswoman.

They are said to have become close last summer, and over the last few months Sir Ken, 54, has been spotted making regular overnight visits to her riverside apartment on the South Bank.

He uses his official car and chauffeur, parking discreetly around the corner. After his visits, he is driven to his office near the Old Bailey.

At one meeting, the pair were seen sitting for an hour at the bar of the Real Greek restaurant near her home, drinking lager and eating souvlaki and tzatziki. Sir Ken, knighted at the New Year, paid the £26 bill and left a £2 tip.

His wife of 27 years, Linda Zuck, 51, head of independent television company Illuminations, is said to have been unaware of the relationship until now.

An ashen-faced Lady Macdonald left the four-storey £1.5million north London house she shares with her husband just after 9am today, refusing to comment.

The mother-of-two had earlier briefly appeared at her front door to collect her post and seemed startled to find photographers waiting outside. There was no sign of Sir Ken at the house.

A neighbour said: "Linda is a lovely woman who has been very distressed since finding out the news yesterday. Her eyes are red and blotchy from crying. She had no idea this was going on."

Unmarried Ms Brimelow - described in Management Today magazine as a "leading lady" of her generation and tipped to become a Queen's Counsel - also refused to comment today.

As well as criminal defence - her clients have included Vinnie Jones - she has acted as a legal adviser to East-Enders and has helped death row lawyers in Jamaica. She has practised at the Bar since 1991, and is a member of the chambers of Andrew Trollope in Fleet Street.

She lists her hobbies as kung fu and kickboxing, and has previously spoken of how she was sexually harassed, at the outset of her career at the Bar, by a senior married colleague who presented her with a negligée and a note inviting her to spend the night with him.

Sir Ken, a leading criminal defence QC, co-founded human rights chamber Matrix with Cherie Booth QC. His 2003 appointment as CPS chief was overshadowed by claims that he was a "Blair crony" and the revelation that he had been fined £75 for sending cannabis through the post when he was a student at Oxford. But he has been praised for overhauling a demoralised CPS.