i'm no mechanic but u say these noises are rattles! there's no way thats big end bearings, they are always a big knocking sound, and on full revs will sound worse if u let off the throttle to half revs then rev straight up again!
This is why im looking forward to the Mini garages diagnosis, his first update was "just drove it up the road your big ends have gone" to which i said investigate.
Just had the same noise in a 1275 and the sound travelled through the fan. Ended up being the clutch letting go slowly but surely
this is interesting as the noise sounded like it was coming from that area which is why i changed the waterpump as i thought it may of been knackered bearings. New slave + Master cylinders as it wasnt always going into gear used to take a few pumps of the clutch.
