Glasses direct have pretty much constant offers of BOGOF AND 50% off, working out at £31.45 for the £55 frames with the cheapest lenses.
This deal on Groupon, takes it right down to £22.95 including postage. I know groupon deals frequently get panned, but this seems like more of a diamond in the rough.
Have used Glasses Direct a lot of times, and very happy with everything I have received.
11% Quidco at Groupon at the moment, bringing this down to a possible £20.86.