Rosemary McKenna, one of Tony Blair's most loyal supporters at Westminster, intends to step down as the MP for Cumbernauld, Kilsyth and Kirkintilloch East at the next General Election, she informed her local party today.

The former teacher, 66, told The Herald that she had decided it was "time to give up"

and let a new generation take charge. "I've had a wonderful life in politics but it's time for me to go. I thought that 40 years in politics was long enough. It's time to allow someone else to take up the baton."

Her constituency is one the Scottish Nationalists would dearly love to grab from Labour's clutches but with a majority of 11,562 at the last General Election, it is difficult to see them making any headway.

It is thought that the local Labour Party will choose the person to succeed Ms McKenna as its parliamentary candidate in the next six weeks or so. One name in the frame is that of Greg McClymont, 36, raised locally, who is a Fellow and politics lecturer at Oxford University and was a speech writer for John Reid, the former Home Secretary.

As boundary changes meant a reduction in Scottish MPs at the 2005 General Election, there were suggestions before that poll that Ms McKenna might step down as Cumbernauld and Kilsyth's MP to make way for Mr Reid whose constituency disappeared under the shake-up. It was suggested Ms McKenna was offered a peerage, but declined. In the end, Mr Reid took over Airdrie and Shotts, the former constituency of Helen Liddell, who left Westminster to become Britain's High Commissioner in Australia.

The daughter of a publican and a shopkeeper, Ms McKenna was educated in Glasgow and for 20 years from the 1970s was a primary school teacher. She began her involvement in politics in the late 1960s and for 12 years was on Cumbernauld and Kilsyth District Council, becoming provost and later leader. She went on to become president of Cosla, the Convention of Scottish Local Authorities.

Ms McKenna entered Westminster in Labour's historic landslide of 1997 and was a Parliamentary Private Secretary at the Foreign Office for three years. She has sat on several Commons committees, most notably that for Culture, Media and Sport, of which she is still a member.

She said the highlight of her Westminster career was its very beginning. "It has to be May 1997. It was a new dawn. Over the years, I have seen the towns of Cumbernauld, Kilsyth and Kirkintilloch change. I now stand outside supermarkets and see the prosperity among the people compared to 1997. This community has virtually no serious unemployment whatsoever. In 1997, there were third-generation children in families that never worked. That's been eradicated. That to me is the greatest thing we have done."

Showing loyalty to the former Prime Minister, Ms McKenna said her low point at Westminster was the way "the media hounded Tony Blair out of office". As for his successor, she said Gordon Brown had had "a fantastic start" and would prove to be "a very successful Prime Minister".

Beyond Westminster, Ms McKenna said she had no intention of going to the Lords but would "love to do something with broadcasting", a particular interest, and is looking forward to spending more time with her family, her four children and six grandchildren.

As for saying farewell to the Commons, she added: "I'll miss being at the heart of decision-making but I promised myself I would not be one of those people shuffling about the place in my 70s."