I just bough a 55″ LG 55UQ80006LB 4K from Argos, a bargain at £349, also came with a free £50 Argos voucher!
Compared to my previous 49″ Panasonic the picture quality is excellent!, looks much more realistic and the sound is also a big improvement.
Please excuse spelling/typos. Apart from being a clot it turns out I had one on my cerebellum that's now causing various problems!