I've done this twice, but never again. Unlike DOH, DXB and BAH, RUH isn't equipped to deal easily with in transit passengers. They insist that you enter the country via the immigration desk which, of course, is not possible without an entry visa.

Both times I alighted the BA flight and was marched off to an office to speak to an immigration officer. The first time it happened, I explained that I didn't want to enter the country and therefore didn't have a visa, but wished to turn right round to depart on the same aircraft on which I'd arrived. Half an hour later I was in the BA departure lounge.

However, the second time I tried it I was travelling with Mrs Full Score. This was completely different. FIVE army officers got involved, all wielding automatic rifles. My wife was treated as if she came from another planet - they wouldn't recognize her existence. For two hours I pleaded with them - only one spoke English - the BA staff were impotent to do anything, and the immigration officials simply shrugged their shoulders even though I['d explained the reason for starting my RTW at RUH. Eventually, we made the departure lounge with ten minutes to spare. But it was SCARY. I envisaged that we might be held in custody overnight since we had no entry visas and the BA flight is the only one each day.

DON'T DO IT. At the very least, have the proper entry visas - there's just enough time to enter the country and then check-in for the return BA flight - with luck, you can print your boarding pass online before leaving LHR. Or spend a night at the airport hotel. Since RUH is the cheapest AONEx starting point, the extra cost would be negligible and you'll have peace of mind.