British stuff is a little tricky to date.
The dennisons had Newley press studs, the 77 ones did, the 84-86 did and the first run of the newer print.
The newer jackets have the wider poppers that rattle. The early ones are brass, the later ones are brass dipped almost , brass coated silver poppers painted black.
Cloth is the same , if the print has large shapes and seems sparse then it's early, in the mid 80's the MOD added extra shapes to DPM and shrunk the print. The print then got darker colours and when it was printed on the yellow cloth the colours went super dark.
The cuffs too , the early ones the cuffs feel a little more rough with means they are probably made of wool, the later ones are soft so could be a wool mix.
You know when you have a later one when you put it against a British made one.