Is this a branch of the Bettys that is also in Harrogate? Excellent but as said earlier a tad pricey…

Yes, it is – http://www.bettys.co.uk Shame they haven’t dedicated a page of their website to the mirror; there’s only a small mention of it on their York page:-

A few years after Bettys opened its doors in York war broke out, and Bettys – in particular the basement ‘Bettys Bar’ – became a favourite haunt of thousands of airmen stationed around York. ‘Bettys Mirror’, on which many of them engraved their signatures with a diamond pen, remains on display today as a fitting tribute to their bravery.

Not sure why they said a diamond pen, it’s more likely to be a diamond ring.

Dean.