“I fear it might have some considerable influence on it, with a very good result like this for us, the prime minister [James Callaghan] won’t be anxious to go to the country, because he’ll be a sure loser.”

So remarked former prime minister Margaret Thatcher, who died today, on the effect of the Conservative victory in the Ilford North by-election of March 2, 1978 on Labour prime minister James Callaghan.

The by-election, triggered by the death of incumbent Labour MP Millie Miller, saw Conservative Vivian Bendall defeat Labour’s Tessa Jowell with a 6.9 per cent swing from Labour to the Conservatives.

Not without controversy, the Ilford North race followed Mrs Thatcher’s infamous “rather swamped” interview for Granada TV’s World in Action programme in January 1978.

Asked on the programme about immigration Mrs Thatcher suggested the British people feared they would be “rather swamped by people with a different culture”. The interview, triggered a vicious debate on immigration, which forced the issue to the front of national politics following a year of riots and action from the National Front (NF) in 1977.

The timing of her comments was seen as an attempt to win back Conservative voters who had defected to the NF in response to the moderate leadership of Edward Heath and to ensure Bendall’s victory in Ilford North, where she visited on February 21 1978 to help campaign.

The NF marched through Ilford town centre in the run up to the by-election.

In an interview with The Times Mrs Thatcher, who had opposed Bendall’s calls for the NF march to be banned, claiming it was a police matter, accused the Labour party of ”vilification on the national immigration issue”.

Shifting the immigration debate back to the mainstream seemed to achieve Mrs Thatcher’s goals as Bendall won with a majority of more than 5,000 votes with the NF beaten back into fourth with only 4.7 per cent of the vote.

Writing later to her daughter, Carol, about the period from the World in Action interview to the Ilford North by election, she said: “The Labour Party have called me everything under the sun, but we have had about ten thousand letters (extra) - all of them, save a handful, in fervent support.

“Ted Heath said I hadn’t got it right and Enoch Powell said I hadn’t got it right, so I must have got it about right if they are both disgruntled.”