SIR Keir Starmer was warned in the Commons today that he could not write a “blank cheque” in support of Ukraine.

At Prime Minister’s Questions, Tory leader Kemi Badenoch placed her party on the sceptical side of the gung-ho premier, who favours the continuation of Kiev’s fight to expel Russian invasion forces.

Ms Badenoch told MPs that the Conservatives supported “efforts to resolve this conflict, but we cannot write a blank cheque.

“If British peacekeeping troops in Ukraine were attacked, whether directly or via proxies, we could be drawn into conflict with Russia. Can the Prime Minister reassure all those who are concerned about the UK being drawn into war?”

Of course, Sir Keir could offer no such reassurance, beyond claiming that it was not government policy to seek war with Russia.

The Tory leader backed Labour in its drive to ensure that Washington does not end its military support for Europe, but she warned against backing any European “go it alone” initiative.

“Without this country’s greatest ally, any peace agreement would place a terrible burden on Britain and our taxpayers,” Ms Badenoch added.

Her remarks indicate that the bipartisan unity on the Ukraine war, which has grown since Sir Keir embraced Tory policy on boosting arms spending at the expense of overseas aid, may not last forever.

It would seem that the Tory leader is tiptoeing towards a Trumpian position — unsurprisingly, since she fears the rise of Reform UK even more than Sir Keir does and her own proclivities as a culture warrior outweigh her geostrategic bandwidth.

She has been almost the only senior politician not to, in some measure, deplore remarks by US Vice-President JD Vance implying that Britain and France are just “random countries” without recent war-fighting experience and therefore unable to deploy effectively in Ukraine.

While several Tories condemned the insult to Britain’s martial valour, Ms Badenoch insisted that there was no need to get upset and backed Mr Vance’s own claim that he had been talking about an unspecified somebody else.

Sir Keir, of course, milked the moment and started Commons questions with a tribute to British soldiers fallen in recent imperial adventures, including Afghanistan and Iraq, in both of which they fought alongside the US. Both, he did not add, failed disastrously — a background fact to the debate about deployment of troops to Ukraine which none in Parliament care to mention.