TomJoad. The, effectively, "what's in it for the UK" question can give a very narrow and bottom line balance sheet answer. It could be used for any other part of the UK to create a very divisive and, perhaps, corrosive atmosphere. The same question might be asked of the Scousers/Woolybacks, Geordies, Brummies and Janners. It's shared history, pride in contribution to combatting past hard times and past contributions to placing these small isles and relatively tiny population so far up the World Nations league.
Are the past sacrifices of Jock Regiments so easily forgotten? let alone those lads who served and still serve in English Units and the British Armed Forces in general.