According to Hargreaves Lansdown research conducted in May, a triple lock pledge would sway 54% of people aged 55+.

For retired people the percentage is understandably even higher at three-fifths, or 61%.

The figures show that the older vote will prove crucial, according to Helen Morrissey, head of retirement analysis at Hargreaves Lansdown.

She said: “We knew issues such as the triple lock would prove decisive. We are deep into general election campaigning territory now and it’s clear the retiree vote will prove vital.”

Other figures from the research underlining that showed that almost half (49%) of over 55s said a party who voted to axe the triple lock would be less likely to keep their vote. For retired people it was a majority at 52%.

More than a quarter (26%) of the over 55s said they would be more likely to vote for a party who said they wouldn’t increase state pension age while 38% said a pledge to increase state pension age would make them less likely to vote for a party.

Meanwhile more than one-fifth (22%) said they would be more likely to vote for a party that cut income tax. That could mean the Conservatives Triple Lock plus pledge could prove popular.

Ms Morrissey said: “The Conservative announcement of the Triple Lock Plus will prove popular not just with those who would vote to keep the triple lock but also those concerned about the impact frozen tax thresholds are having on their income tax bill.”

But she pointed out that there’s been little said as yet about the prospect of state pension age having to rise again to contain spiralling costs.

She said: “It’s the unpleasant dilemma at the heart of state pension debate that isn’t talked about enough. We know the cost of state pension is enormous and is shouldered by a smaller working population.

"In the face of a burgeoning bill there’s every chance the government will pull one of its key cost containing levers and hike state pension age. Such a move would prove highly unpopular with the retiree vote – almost 40% of over 55s said such a pledge could make them vote elsewhere.”

The status of the lifetime allowance will also be important to wealthier pensioners., she added.

• The data was taken from a survey of 2,000 people carried out by Opinium on behalf of HL in May