Thanks, xman ... our long term trusted independent garage found a fairly small amount of play at the nearside diff because of bearing damage, but enough to leak some oil at the seal ... it's booked in for work to be done in a couple of weeks time & should be done in 5 days, to remove gearbox / send to specialist be dismantled, inspected, flushed, new diff bearing / refitted by end of that week, all for estimated £1,200 inc. VAT (all assuming no further damage is found, of course ... & they recommended & will do new clutch plates at the same time given its 50k. miles for another £200 inc. VAT). I'm wondering if the bearing was damaged by clouting a big pothole ..? So many of them this year, and with care we manage to avoid almost all, but inevitably got caught by a couple through winter months ... I guess the diff. bearings on front wheel drive cars (esp. the nearside 'potholes side', of course) are vulnerable in way that diffs. on rear wheel drive ain't ...