I would strongly recommend 'Song For Someone' (psi). A large group recording from the mid-1970s with stellar British big band lineup (all the usual suspects - Taylor, Winstone, Alan Branscombe etc) plus Tony Oxley, Evan Parker and Derek Bailey. Originally recorded for Incus Records and an incredible amalgam of traditional big band and Euro free-jazz forms. Hugely under-rated and near-unknown album, rare on vinyl and buried for circa 30 years before the CD came out.
My favourite Wheeler is probably the infamous and rare 'Windmill Tilter' (Fontana). Almost a prototype run for 'Music For Large and Small..'. I hope that it comes out on CD format in the not too distant future..