Yes, let's have an English Parliament alongside a UK one if the Scots vote "No"
The use of proper nouns as adjectives is now almost de rigueur in certain contexts.When I was at Primary school I recall an early exercise in my English class where we had to say what the adjective was for various Proper nouns - including country names. So for "Spain" we had to say "Spanish", for "Wales" it was "Welsh" and for " Germany " "German" - and so on. There were no rules, the adjective endings were arbitrary and we had to learn them.
Today, especially but not exclusively, in sports commentary you often hear the noun itself used as a pseudo-adjective. So a footballer is described not as a "Spanish" goalkeeper but as the "Spain" goalkeeper. My use of different articles here shows why this happens. The indefinite article use - "A Spanish footballer" - refers to the players nationality. The use "The Spain goalkeeper" has the definite article and the take out is that the player is not just Spanish, that is implied, but that he is in goal for the Spanish national team. Very clear.
"Spain" is not an adjective however and to use it as one is grammatically incorrect. In the specific case I have quoted it is as I say clear, but wrong. Often, though, the noun is used as an adjective when there is no conceivable reason to do so. Let’s say you are watching a cricket match between England and Australia and you wish to refer to the latter’s wicket-keeper. The correct usage is “Australian” (the adjective). That is clear and unambiguous. It refers to his nationality and to the team he is playing for. So why would you call him the “Australia” wicket-keeper? This is all too frequent I’m afraid.
In the “Spanish footballer” example there is some ambiguity. I would always prefer to resolve this by using the longer, but grammatical, "Spanish international goalkeeper" to the shorter but ungrammatical "Spain goalkeeper" but suspect I'm in a small minority on this one!
Most, but not all, nouns have related adjectives.The adjective to “Wood” is “Wooden”, to “Grass” its “Grassy” to “Wool” its “Woollen”and so on. But "Cotton" is a noun without a related adjective so if your shirt is made of cotton it is a "cotton shirt" - we use the noun and it effectively becomes an adjective in this use. When it comes to proper Nouns there is sometimes a related adjective (most countries have one) but not always. Manchester has one (Mancunian) but London does not. So while we can say something like “Mancunian weather” there is no similar adjective for the capital city so we have to use a more lengthy construct.
In short this is a plea, which will almost certainly fall on deaf ears, to use adjectives rather than pseudo-adjectives (nouns as adjectives) wherever possible. And where there isn't one to find a grammatical way around the problem!
The Commonwealth stretches back to 1948 - the year Britain finally gave up that Jewel in the Imperial Crown - India. I doubt that there was ever much point to the Commonwealth even then. It was a device to soften the blow of the loss of Empire and in part to reduce the guilt that Britain rightly felt for its Imperial past. If, the logic perhaps went, once colonies can voluntarily gather together in a "Commonwealth of Nations" then the British Empire can morph into this new construct so proving that the Empire had a valuable unifying value even across disparate nations. But the only thing that held the Empire's countries together was sovereignty - the British Monarch was the titular head of state of all of them. Take that away, and the logic breaks down. True a few Commonwealth countries still have The Queen as head of state - a preposterous anachronism that will surely go with her passing. But that aside there is nothing holding the Commonwealth nations together except pomp and waffle.