I've just had this through from Groupon:
LG 42 in 1080p backlit LED - £399
Obviously NTDWM, seems like a deal though, other cheapest deal on Google shopping is £440.
Call Comet & get them to not just match the price, but beat it including delivery. I did this about a week and a half ago with a fridge freezer and a dishwasher (even though one of the cheapest prices was an internet voucher code of their own for one of the items). I saved nearly £200 over their current advertised price.