Only for the vigil. As a general rule, former and retired military in the UK do not wear military uniform. Members of the Royal Family who do wear uniforms, do so due to a military role (Colonel-in-Chief of a specific regiment, for example).
The Duke of Sussex relinquished his military roles when he ceased to be a working Royal and moved to California. He also lost his right to wear the uniform.
The Duke of York lost his right to wear a uniform when he was removed from being a working Royal due to being an idiot
OK thank you for this information