I don't think Barnes Wallis designed HOTOL. He died in 1979.
The link says the design owes a lot to the "swallow" design that he came up with.
A lot of these rocket transportation ideas are just too expensive to be commercial. You might love the idea of being zoomed into space to touch down in Australia 5 hours later but £2,000 a ticket is a steep ticket price, and that's their estimate from 2 years ago
Consider this too. If you need to get to the other side of the world quick - you ring up and someone says "Yes certainly sir, we do 3 flights a week - we can fit you in the day after tomorrow"
Not really commercially viable is it?
Still the EU was going to give the project 10 Million to evaluate - don't know if that happened or whether belts were tightened after the banking crisis
http://www.esa.int/es...ng/SEMTCU0P0WF_0.html
and Google LAPCAT II