They won't tell you but most big retailers negotiate their own exclusive model numbers with TV manufacturers, so identical sets technically aren’t the same, making price comparison harder. Also, the £50 HDMI cable does nothing more than the £10 one. A digital signal arrives or it doesn’t. What matters is the certification category: Premium High Speed carries 18Gbps, plenty for 4K streaming. The real problem could be the length, more than about 15 feet, build quality starts to matter.