Britain’s slimmed-down monarchy has been left vulnerable in wake of cancer diagnoses

Fewer engagements are being conducted, and possible role of Harry as regent could raise constitutional issues

A decade ago, the royal family notched up more than 4,000 engagements in a year, travelling across the UK and criss-crossing the globe.

The then Prince of Wales travelled to Saudi Arabia, Mexico and Colombia; Prince Harry went to Brazil and Chile and the Queen and the Duke of Edinburgh carried out more than 660 engagements between them, including trips to France and Italy.