The British Space Agency? Is that the two old men with a box of fireworks?
Great. Inviting the other nations in means a repeat of the ISS fiasco. Bloated budgets, limited success and nothing to show for taxpayer dollars. In 20 years space will be dominated by private interests and NASA will be just another hasbeen worthless government agency that refuses to die long after it's usefulness has passed.
NASA should rather try to make an alliance with American industry and keep American space exploration American.
He should be appealing to the leaders of Microsoft, IBM, General Electric, Boeing, Exxon Mobil, Hewlett-Packard, and 3M: offering a 100 billion dollar prize plus 80% of the mineral rights for any consortium who can build a working permanent station on Mars and occupy it for a year.
Winkle-tinky all over this idea. The US paid for almost all the cost of building and orbiting the International Space Station -- including paying for some of the Russian stuff -- and gets almost no use of it, all of the blame, and none of the credit. If other countries want to go to Mars, let them bring back our flag.
When you take the lead in these areas: development, cost, implementation, operations, and infrastructure, then you can be the one who gets to ask other agencies to sign on. You guys always want to be in when it's on the cheap.