On College Green the bravest, ugliest tourists have shed their overcoats and donned shorts. In Great Peter Street the tall, shabby-genteel Edwardian blocks of flats are sporting window-boxes of daffodils and crocuses. A bush of yellow forsythia peeks through the newly painted black railings that line the Queen Anne terrace of Lord North Street.
But what season is it in the building that lies - round the corner - in the shadow of the imposing baroquerie of St John's, Smith Square? Give me a moment to put my change and keys into a little polythene bag and pass through the metal detectors just inside the doors. Wait, while Venetia or Cordelia in the sky-blue cardigan and Hermes scarf, checks my credentials and hands me a sticky badge; while pin-striped, spotty Tarquin thrusts a bundle of press releases into my hand.
Here I am, inside a dark theatre. At the back is a projection and lighting booth, manned by three more Tarquins. Round the walls are posters proclaiming the dangers of electing a Labour government. Extra Venetias and Tarquins appear at intervals along these walls or sit, singly, in various parts of the room. Music (Vivaldi perhaps) enters from some hidden source.
Near the front, seven or eight of Britain's finest political correspondents and editors huddle together for companionship. To their side and behind, watching them with zoological interest, is the diminutive (but perfect) Alan Duncan, MP for Rutland - seconded for special election-time duties to the office of the Chairman of the Conservative Party.
Who now enters, accompanied by the straight, stiff figure of the President of the Board of Trade, Ian Lang. Mr Lang sat on a ramrod when young, and carries it still within - at once a handicap and a source of inner strength.
But it is Dr Mawhinney who captures the eye. Just a few weeks ago he seemed to be bearing the sins of his party Dorian Gray style, in his face. That yellow skin, those darting fierce but frightened eyes, that odd, agonised revealing of the teeth - which might give a name to a new verb, to Mawhinney: to smile a ghastly smile.
Today - to my surprise - that death's head grin is gone. The smile is almost gentle, Mawhinney's adumbration of the many sins of Labour is perfunctory and lacking in malice. He takes and evades questions with a resigned air, as if to say "you are journalists and must ask; I am a politician and must not answer. It is in our natures."
Though the ostensible purpose of the event is to unveil an unflattering letter sent by Mr President Lang to Mr Padraig Flynn - Irishman and Euro- Commissioner - no one (least of all Dr Mawhinney) is interested in the new threat to Britain's jobs posed by devils on the Continent. But there is a job to be done, and tomorrow Dr Mawhinney will be here with Peter Lilley, and the day after that with someone else.
Outside, beyond the metal detectors, men are digging up the road in Lord North Street. High up in the Great Peter Street flats an old lady with untidy hair leans out of her fifth-floor window and waters her ivy. A gaggle of schoolchildren passes down Millbank on their way to the Abbey. As Dr Mawhinney knows, Spring comes, life goes on - and governments fall.