From the public railings of Buckingham Palace, the soldiers of Her Majesty’s foot guards look as immaculately turned out as ever this week.

But when the bear-skinned troops march past as they perform the changing of the guard, spectators with a keen sense of smell may well detect something amiss.

The malodour can be traced to the neighbouring Wellington Barracks, home to the historic regiments, where a breakdown of the “ancient” boilers has left guardsmen without hot water for days.