This was recently listed here as an Argos deal at £779 plus delivery of £3.95. I was about to order one but found a cracking deal at AO.COM for £701.10 plus FREE delivery. The gross price is £779 but there is a discount code of 10% (SONY10) which reduces the price to £701.10. I have ordered from AO.COM before & customer service (particularly delivery) in my experience is top notch. I also got a further 1.57% which (if it tracks, ours did) gives a further £11 discount which reduces the cost to £690.10 with free delivery!
Sony 55XD7005BU Freeview HD & YouView HD Smart 4K Ultra HD TV £701.10 with code SONY10