I dont think that anyone in the 1600's would think the newly independant Dutch nation would prosper, how wrong they were
If Britain got stuck in a war the Welsh and Scotts could revolt and be allies while the Irish liberated Northern Ireland
You see,
The Dutch had the wonderful advantage of not being attached to the Spanish mainland.
The Dutch had control of some of the richest trading spots of Europe.
The Dutch enemy, Spain happened to be France, England and the Ottomans.
The Dutch population was not pitifully small nor spread out in many rural farms.
The Dutch was not directly, centrally or strictly, governed by the Spanish.
Wales was incorporated into England.
A Welsh Dynasty ruled England. Followed by a Scottish Dynasty. (The English hasn't ruled themselves since 1066. Norman French...Welsh...Scottish...German...Even more German...)
There was a preference to Protestant English Rule than Papist French/Spanish Rule.
Wales was poor in people and resources.
Now if modern day Britain got stuck in a war, then the Welsh and Scots would defend Britain. Cause Wales and Scotland are part of Britain. They are separated from the English but united as the British. If would have to take some big turd behaviour on the part of the English, say dissolve Scot and Welsh Parliaments and then oppress Celtic culture for Wales and Scotland to rise up against their sister nation.
What we have here, is a case of petty nationalism!