Sir Keir Starmer has been dealt a crushing blow just weeks into his tenure as Prime Minister after it was revealed Labour Party membership has slumped to its lowest level in ten years.

According to the party’s official records, it lost 37,000 members last year, with its membership totalling 370,450 at the end of 2023.

The figure marks a new low for Labour membership under Sir Keir, compared to 532,000 members recorded in 2019 when Jeremy Corbyn was leader.

It is Labour’s lowest membership since 2014, the year it brought in its “one person one vote” system offering members and MPs equal say when it came to leadership contests. Following the change, membership doubled to 388,000.

The nine percent dip also represents Labour’s sharpest annual decline since 2003, when it fell 13 percent from 248,300 to 215,000, likely the result of misgiving many had about the invasion of Iraq.

Labour nevertheless reported a less-than-expected loss of £851,000 – it had been bracing itself to be in the red by £2.5 million throughout 2023.

Party treasurer David Evans said this was a result of “an increase in high-value donations”, investment in staffing levels and technology, and a relocation to a “more appropriate” head office.

Labour was not the only party recording a fall in membership in 2023, with the Liberal Democrats shedding about 11,000 members.

The Conservatives do not publish membership figures, but income from membership fees declined from £1.97 million to £1.5 million, maintaining a downward trend from £2.21 million in 2019 under former PM Boris Johnson.

Both the Lib Dems (£271,258) and the Tories (£17.9 million) ended 2023 with surpluses, the latter’s coffers swelled by a £10million endowment from Lord John Sainsbury.

Tory treasurer Alan Mabbutt said: “The board remains confident that sufficient funding will be generated in 2024 to build on this positive result and support the spending ambitions of a general election campaign.”

Both Reform UK and the Green Party saw their party memberships grow.

Although Reform does not publish its members, a spokesman told The Daily Telegraph its membership had grown “significantly”.

Nigel Farage’s party also reported donations of £1.3 million for the year, almost twice the total for 2022, although just £295,000 was eligible to be reported to the Electoral Commission.

At the time, donations of less than £7,500 did not have to be reported but has since increased to £11,180.

The Greens, led by Carla Denyer, now has 53,000 members, up fro 49,000 in 2019.