You're right, you're right, I think I'll have to give in and get a roof box. The stowaway will always be in my mind though as what could have been - especially when we go away for 2weeks at a time, could really do with that bigger box on the back! Not put it to the boss yet, so there is always hope, however small!
thanks guys for all your advice, most helpful site I have found! No doubt I'll be back soon with more questions.