A member here once said this could be had at M&S for under £30, but none near me stocked it.
Finally stumbled across it this morning at M&S Victoria (Cardinal Place), and it fell into my basket. Not marked as reduced to clear (see photo) so hopefully elsewhere too.
The line is discontinued, having been replaced earlier this year by a NAS edition marked only as 'Small Batch', where the barrels are aged between 8 and 12 years (apparently due to too much demand for the 12 year old). The NAS is about £36 on Amazon and the 12, where still sold, is typically £35-36 too.
A lovely drop in my experience, having had it in bars aplenty (hic).