London | To put on a coronation parade fit for a king, Britain’s armed forces have to overcome a daunting challenge: how do you get 4000 soldiers and their 20 different military bands, who have flown in from dozens of countries, to march in perfect lockstep?

As they lead the newly crowned King Charles and Queen Camilla back to Buckingham Palace from Westminster Abbey on Saturday, they’ll be spread out along hundreds of metres and they’ll be drowning in noise – making the task of keeping a uniform step near impossible.