Don't know what we are going to do!! We are five people adult size with five large suitcases and assorted carry ons. Three of the five are brothers ages 20, 19, 15 and it will really be miserable to be scrunched up in the back seat. The 7 passenger van won't fit us. I can not find anywhere in London to rent anything bigger.

Well, assuming you don't want to split up into two cars or take the train, can you ditch the five large suitcases and learn to live with just five carryons? You don't seem to have much choice otherwise, but good luck.

Can you rent or buy a rooftop luggage rack?

I think luggage control is key. I would not want to leave my luggage strapped to the top of the van (You will look like the Beverly Hillbillies!) Tell everyone they can have ONE 22" suitcase and ONE SMALL carryon. That should work with a 7 passenger van.

Why not a luggage rack--we saw plenty of European vacationers with them on their cars.

Repack! No one needs a large suitcase plus assorted carryons for a typical trip to Europe - even if you are going for a month or more. Each of you should have a 22" roll-on and not much more. Sorry, but your problem is easily solved if you pack right. Traveling right involves traveling light.

especially those boys...all they need is some jeans, undies, socks, t's and a couple of shirts....sneaks and a decent pair of shoes....you on the other hand????
don't take too much...have stuff washed or cleaned...
son't start off with the boys mad or you are in trouble....

another hillbillie idea...how about a small trailer...you see lots of them in europe??
and yes a roof rack or use a ski rack if you want to disguise your hillbillieness...