If Spain is entitled to blue vestments on December 8 because of its role in promoting the Doctrine of the Immaculate Conception, I would have thought that a fortiori England would be even more entitled.
The use of blue among Anglicans for Advent is part of the old (Percy 'dishonest plagiariser' Dearmer) idea that you show you are are a loyal Anglican and not a beastly Romaniser by discovering details in medieval English usage which diverge from modern Roman custom, and then proudly parading them. An example of such Dearmerism, so I have been told, survives at Exeter Cathedral, where they use blue in Advent. If true, this is all the more daft because, whatever they did elsewhere in England, at Exeter Bishop Grandisson's Ordinale (14th century) clearly required violet (the dear Burgundian old boy very naturally preferred to operate iuxta morem curie Romane). Incidentally, in case any of you were wondering, its Latinity does carefully distinguish between violet and blue.
It allows, however, although optionally (non inconvenienter indui possent), the use of blue on double feasts in Advent and Lent. Since the Conception was a festum duplex, we have here "English" precedent for using blue on December 8.
Rumour has it that the use of light blue for feasts of the Theotokos is common in the Russian and other 'Slavic' Churches. Is this by Western influence? I find it a little unexpected in as far as in Byzantine iconography our Lady is normatively clad in red.