Former Lance Sergeant Bernard ‘Barney’ Cresswell joined the Grenadier Guards in 1943 and found himself patrolling the corridors of Windsor Castle soon after.
Barney said: ‘I was in Victoria barracks at Windsor, we'd finished three months of field training, and then we were posted to castle garrison.
‘We lived in the stables, we didn’t do static guard duty, which was a separate unit, we used to patrol around the corridors.
‘I’ve learned since that there was a big scare on at the time that German paratroops might land on the castle and hold the Royal family.
‘I suppose being a young squaddie, it didn't enter my head, you're just doing what they said to do, you’re just given your orders and you get on with it.’
Barney said it was ‘a surprise’ to be taken to Windsor Castle, where he and his family were met and shown around by the regimental quartermaster sergeant of the Grenadier Guards, warrant officer class two David Roper.
RQMS Roper said: ‘We had been planning this as a surprise for Barney and his reaction didn’t disappoint, he is an inspiration to us all, it was an honour to meet him.
‘He is a very modest man who you can tell just got on with his job and did it extremely well; I know I can speak for the whole regiment when I say thank you to Barney and all those who served alongside him during those dark days.’
Reflecting back on his time at Windsor Castle, Barney said: ‘You're part of history, aren't you? And of course, she [The Queen] became Colonel of the regiment.
‘I've always been proud and I'm a royalist anyway, I'm quite proud of that.’
After guarding Windsor Castle, Barney was sent to France, landing in Normandy 12 days after D-Day - for which he was awarded a Legion d'honneur.
He and his unit walked most of the way through Europe, serving in Berlin during the aftermath of the war, and he was de-mobbed in 1947.
Barney then served as a police officer for 30 years, and volunteered for the armed forces charity SSAFA at the Hampshire branch in Havant.
Barney said: ‘They’ve got an office in Havant which opened in 1946, which is manned by volunteers.
‘When I retired when I became an OAP I was looking for something to do.
‘I became a case worker, and I was treasurer as well for one time.
‘You go and see service families or individuals, they come to us with problems - anyone in distress. It can be anything.
‘I did that for 29 years, and I only gave it up last year because of my eyesight.
‘It’s very interesting as everyone’s got a story to tell.’