The 16-year-old from Halwill will be representing the Okehampton and District branch of the RBL and says he is 'shocked but honoured' at his selection from 90 branches across the county.
James is the only youth standard bearer in Devon but, since his first duty in Okehampton on Remembrance Day, he has received nothing but praise from RBL members, who are all several decades older than him.
The teenager, who is due to take his GCSEs this year at Holsworthy Community College and is a keen sportsman, is currently taking part in training sessions to make sure the Golden Jubilee Service in Exeter Cathedral goes without a hitch.
Recruited from the Air Training Corp Cadets in Okehampton, James is the first of many young people chosen to represent the local branch of the RBL.
His ambition since a toddler has been to become a pilot and he has a fascination with wartime history. Two years ago he joined the air cadets and was promoted to corporal at the end of last summer.
'I always look after my things and am quite good at drill so I guess that's why they thought I would be good as a standard bearer,' said James, whose late grandfather, Henry Stacey, was an aircraft mechanic during the second world war.
'I have never met the Queen before so it will be quite nerve-racking but it's going to be a pretty special day.'
James' mother, Christine, said she knew her son would come up trumps on the day because he was always good at being thrown in at the deep end.
'We will be watching him every step of the way,' she said. 'I always have a tear in my eye when I see James all dressed up because that is when I realise he is not a kid anymore.'
Mrs Stacey said her son was a confident and capable young man who knew what he wanted out of life which was to join the air force.
'James knows the name of every plane you put in front of him and ever since the age of three he has said he wants to fly an aeroplane,' she added. 'We are all very proud of him for what he has achieved so far.'
Spokesman for the Okehampton and District branch of the RBL Peter Williams said it was marvellous that James had been chosen for such an important occasion.
'He really is doing an absolutely fabulous job and he has put our faith back in the youth of today,' he said.