Minister Tony Blair’s closest allies announced last night that she is standing down at the next election.

Hilary Armstrong, the MP for North-West Durham and one of labour’s longest serving chief whips, announced her departure to party members in Crook last night.

Former colleague Alan Milburn, MP for Darlington, came to the same decision a week ago.

Ms Armstrong denied last night that her decision had any connection with the recent storm over MPs’ expenses – she paid back £5,500- worth of food claims that “weighed on her conscience”.

It was, she said, time to make way for new blood after 22 years and the expenses furore had delayed rather than hastened her announcement.

She said: “It is time for the next generation.

“I will be 65 at the end of next year and feel that it is now the right time to let someone else take up the role.

“I have loved working in the constituency, and look forward to supporting Labour here and nationally.

“I still have lots more to do as the MP, and at this stage just want to thank people who have inspired and supported me over this time.”

The former Sunderland Polytehcnic lecturer made history when she followed her father Ernest into the House of Commons in 1987.

Quick to make her mark, she held several key posts in opposition and in Government until she was promoted to the cabinet as chief whip in 2001.

Her reputation for fierce loyalty to her boss could not keep her in the job when, in early 2006, the Government lost its third crucial vote in as many months.

Labelled incompetent in the press, she shrugged off the hurt and threw her energies into a new twin role as Social Exclusion Minister and Chancellor of the Duchy of Lancaster.

Once she quit the Cabinet following the arrival of Gordon Brown, she enjoyed having more time in her constituency and working for her favourite charities such as Voluntary Service Overseas and Mr Blair’s Sports Foundation, which she will now chair.

She has always called the North-East her home and plans to keep on her house in the centre of Crook.

She said: “By the time of the next election I will have been an MP for 23 years, which is the same time as my father.

“Of course I will miss being at the centre of government and being involved in strategic decisions, but I will still take an interest in projects in my constituency.”