Hurrying into the Commons just in time for the debate on Trident was a fresh-faced Tory backbencher. As he hastened up the aisle, a handful of fellow MPs welcomed him with a little cheer of encouragement.

Beaming bashfully, he slid into the seat next to Sir Simon Burns, MP for Chelmsford – an old hand who will be able to offer his younger colleague guidance.

For now, the pink-cheeked rookie contented himself with listening in earnest silence to the Prime Minister, as she began setting out the case for Britain’s nuclear deterrent.