Paul uses a Mamas and Papas Aria buggy. Unless the Aria is the ideal solution I would avoid Mamas and Papas - really, really awful Customer Service if things go wrong. And they also illegally try and restrict your statutory rights by refusing to offer replacements.
Search for threads by "Rakey". He's worked in babystuff for years and his firm have designed a tri-fold buggy that fits into a MINI.
www.silvercross.co.uk