The Weights & Measures of the Celtic countries is far too complicated to cover in any great detail here, but hopefully you'll get a flavour for the subject from these notes.
From about 1450, the weights and measures of Ireland should have been the same as those of England, but in practice the legislation in Ireland seemed to sometimes be out of step with England. The act of union (1800) created uniformity, but of course the Republic of Ireland went its own way again after 1922, on the formation of the Irish Free State. From 1922 until absorbed into the European Union, Irish weights and measures seemed to stay much the same as the Imperial system. Northern Ireland of course stayed as part of the UK.
The ancient Irish mile is often quoted as 2,240 yards.
The inch in Scotland and England were the same. The Scots ell was of 37 inches, which may be connected to the 'London measure' by which cloth (etc.) was measured by the yard and an inch (la alne et pous) in England around Henry VI's time. The English ell was a yard and a quarter (45 inches).
The ancient Scotch mile is often quoted as 1,940 yards.
The measures in Wales are hidden (to me at least!) by the language. The Welsh had measures of area called the 'erw' (which translates to 'acre'), the 'tyddyn' (='small farm'), 'maenol' (='manor') and 'cantref'(='hundred', as used in English for a division of land, rather than 100).