Have a look at the pricing sticky at the top of the forum. You'll see how the pricing for the UK vs CAI is quite different, even for an LONE4 in the high season. If you're going LHR-CAI as part of the trip, you could save some money and gain a stopover. Study the CAI DONE prices and you may even tempted to go up a class......
LONE4 (from the pricing sticky)
United Kingdom high £1,519
United Kingdom low £1,319
Egypt £1,142