Sketch: Forget rail franchises, this minister clearly knows where his department is

David Heath, the Environment minister, is not Churchill. But he did his best

Obliged to defend the indefensible today, the Transport Secretary Patrick McLoughlin did what any skilled and self-respecting politician in his position would do. He grasped at straws. Or rather at the solitary straw that was available.

Labour's Maria Eagle, after a fairly devastating indictment of the four separate Cabinet ministers that she blamed for what is now all but officially described as the West Coast Main Line Franchise Fiasco, declared that a "nightmare on Marsham Street" was rapidly becoming a "nightmare for Downing Street".

Although McLoughlin's department had long been in Marsham Street, it is now nearby in Horseferry Road – a point that the minister, understandably keen to distract what attention he could from an interim independent report redundantly confirming there were "significant errors" in a "flawed" franchising process, made with relish.

Wondrously, by highlighting the slip McLoughlin, lifted the mood of his anxious backbenchers, making them guffaw with relief – with one even congratulating him on "knowing where his department is". As if a minister's knowledge of the location of his own office would suddenly restore confidence in the government's competence.

Oddly, there had been more MPs present for an earlier Urgent Question on ash tree disease. You don't have to be insouciant about our arboreal heritage to wonder whether this blight deserved the crisis atmosphere in the Commons that greeted, say, Rommel's capture of Tobruk in 1942.

David Heath, the Environment minister, is not Churchill. But he did his best. Rebutting a valiant effort by the Shadow minister, Mary Creagh, to turn this into another government fiasco, he declared gravely that "we will not fail in our fight against this disease because of a lack of adequate resources".

He could not guarantee that no-one had, in Ms Creagh's words, "imported [infected] saplings in the boot of their car". But as a Liberal Democrat he was determined to disappoint Tory backbenchers keen to blame the EU for this airborne invasion of what Zac Goldsmith called our "island nation".

He explained that the Secretary of State, Owen Paterson, could not be present because he was meeting people in Cannock Chase who had "got the disease". This raised the appalling prospect that Paterson himself might become infected with the lethal Chalara fraxinea fungus. Indeed, Heath admitted that he could not be 100 per cent sure it did not "cross species".

Beside this, the Transport statement seemed positively low key. But while McLoughlin put Eagle right on where it was happening, he did not actually deny it was a nightmare.