Defence Secretary Gavin Williamson has met members of the Household Cavalry who will be working over the festive period.
During a visit to Horse Guards Parade, Mr Williamson praised the commitment of the military personnel who will be carrying out their duties to keep the nation safe over Christmas; he said:
"What's quite obvious is their complete dedication to their job, their complete dedication to ensure their ceremonial duties continue, but most importantly their complete dedication to keeping Britain safe and that is what I think all of Britain admires."
The Defence Secretary witnessed the soldiers preparing their horses for guard duty and spoke to those who will be working.
For the horses and riders on duty for the Queen's Life Guard, Christmas morning starts with the fancy dress guard.
Normally the soldiers would be inspected on the cleanliness of their horses and their uniforms but on December 25th the inspection gets a festive twist as the soldiers are judged on their fancy dress costumes.
The winner gets the most favoured stand on Queens Life Guard.
WO Class Two Squadron Court Major Preston says the tradition gives the soldiers "light relief" while working on Christmas Day:
"They will come up with fancy dress costumes that you have never seen before, we have knights, we have people turning up in wheelbarrows as a muck-pile, we get people dressed up as horses, one year we had a soldier abseil out of the accommodation as the [Milk Tray] Man.
"They'll think about it all year and then they'll really push it out when it comes to Christmas Day."
Also on guard on Christmas Day will be the squadrons of Britain's Quick Reaction Alert (QRA), who will be on duty at RAF Lossiemouth and RAF Coningsby, and ready to scramble the jets if required.
Overseas, the Ministry of Defence said there are also more than 5,000 armed forces personnel, with UK troops involved in 25 operations in 30 countries.
This includes 1,000 troops working to combat the so-called Islamic State in the Middle East by training local security forces, as well as those based at RAF Akrotiri in Cyprus.
Personnel are also in locations such as Afghanistan, the Falkland Islands, Estonia and East Africa, and since 1969 British submariners have been on permanent patrol providing the UK's nuclear deterrent.