"Yes of course it would be good to train and retain more UK doctors"
Glad you agree
"I was just cross at Mair's post."
Why? Its a perfectly reasonable position to hold.
"Our students may not fancy training abroad but its an option open to them."
It should be exactly that an option, for those who want it! The fifth biggest economy in the world should not be forcing its own students to go abroad to study as if we are a Third World country!
Is this the future you want for yru granndchildren?
"Travel broadens the mind".
Arguable! It is not a proven fact, nor is the definition of what constitutes a 'broadened mind'. 
However we are not talking about 'travel'. Leaving home for the first time is quite a challenging enough experience for most eighteen year olds anyway, without having to simultaneously cope with all the extra challenges, and costs, of studying abroad. Most overseas undergrads in this country do not come here at eighteen fresh out of school, many are a little older, have often worked, and many have relatives livign here who they live with.
Forcing medical students to study abroad also disadvantages poorer working class student most, those who are more likely to choose a university close to home, and whose parents are least able to help with additional costs or bail them out financially if they get into trouble. They are also less likely to have parents knowledgeable about the differences good and bad livign in the target country presents.
Your comment is I am afraid very ill thought out.