"some 460 km (290 miles) west of Great Britain..."
It's 90 miles closer to Donegal than it is to Britain.
The Ministry of Defence sent an expedition to Rockall in 1971 to blast the top off the Atlantic islet, a newly released report has revealed. The expedition, code-named Operation Top Hat, was dispatched “to lay a flat surface on top of Rockall so that an all round visual light could be erected in the future,” according to a …
Let's not get ahead of ourselves.
Scotland (the nearest permanently inhabited place is North Uist) is still part of Britain.
Here's a map of the agreed EEZ's. The UK doesn't have an awful lot considering her population density.Should Scotland claim the Northern part of the UK's EEZ, England and Wales would have very little to play with.
https://www.arcgis.com/home/webmap/viewer.html?webmap=cf9a73170fcd41ceb320e1292f5f9035
"Here's a map of the agreed EEZ's. The UK doesn't have an awful lot considering her population density.Should Scotland claim the Northern part of the UK's EEZ, England and Wales would have very little to play with."
That might be, but consider that Great Britain still has a number of countries under its commonwealth. So take those in to consideration, compare them to what Scotland, Wales and Ireland have got, Britain isn't doing too badly.
'Interesting how much UK loses if Scotland leaves'
It does depend to some extent on how the lines are drawn. Under the applicable UN Conventions where the land border isn't perpendicular to the coastline it continues out to sea in the original direction. This gives England a larger share of the North Sea than you might think.
Admittedly the SNP don't seem keen on that particular UN Convention...
That would really depend on your viewpoint and lifestyle. If you are a city dweller using public transport to commute, you won't loose much. If you are a mermaid / merman drilling for homeland gas to power your sports-amphibian vehicles, then you might have a lot to loose.
"Extending the UK territorial claims to (possibly exclusive) fishing and mineral rights further into the Atlantic Ocean than previous limits?"
It would need to be permanently sustainably habitable - which it is not. Therefore the Territorial Sea gets extended around Rockall for 12 nautical miles - but not the EEZ.
"consider that Great Britain still has a number of countries under its commonwealth"
I think you must be looking at a hundred year old map of the world; The Commonwealth isn't a political union, and the United Kingdom government has no authority over any of the other Commonwealth Nations' territory, so it makes no difference to the Britain's access to economic resources.
"consider that Great Britain still has a number of countries under its commonwealth"
There will possibly be some upheaval when the Queen dies. Apparently King Charles III doesn't inherit that Commonwealth mantle automatically.
https://www.theguardian.com/uk-news/2017/mar/16/what-happens-when-queen-elizabeth-dies-london-bridge
After BREXIT the Spanish expect to annex Gibraltar.
The Commonwealth isn't a political union, and the United Kingdom government has no authority over any of the other Commonwealth Nations' territory
Yeah but nah but err...
The Statute of Westminster, of 11 December 1931, was a British law clarifying the powers of the Commonwealth Dominions. It granted these former colonies full legal freedom except in those areas where they chose to remain subordinate to Britain.
Buuuuut as reaffirmed in a recent court case, there is the concept of parliamentary sovereignty (also called parliamentary supremacy or legislative supremacy) is a concept in the constitutional law of some parliamentary democracies. It holds that the legislative body has absolute sovereignty, and is supreme over all other government institutions, including executive or judicial bodies. It also holds that the legislative body may change or repeal any previous legislation, and so it is not bound by written law (in some cases, even a constitution) or by precedent
@Diogenes; Statute of Westminster
Parliament could indeed repeal the statutes that give effective independence to the dominions. It can also legislate to make it an offence to smoke on the streets of Paris (as a famous constitutional lawyer once wrote), but that does not mean that it could enforce those statutes in either case. Canada, Australia, New Zealand et al might just refuse to implement them.