Woe, woe and thrice woe. Just got back in the car, started the engine and about 10 seconds later a sound like an old tyre blowing and the rear end dropped lower than a snake's belly. Initially I thought just the offside but the nearside dropped as well.  I don't think it's one airbag, seems more likely to be a hose broke or come loose. Opinions welcome. The car is 13 years old.

Hello Ian,

Sorry to appear unhelpful, but I would think it’s virtually impossible for anyone to identify the actual cause without inspecting the vehicle, and to attempt to do so is likely to simply lead to wasting valuable diagnosis time. 

If the car is drivable with caution and respect, then I would have thought any reputable local garage should be able to identify a cause of what appears to a fairly catastrophic failure.  

Kind regards,

Gareth.

Update time. On Monday afternoon/evening I crawled the car up to my local (trusted) garage and asked them to pop it on the ramp so's l could check underneath. Sure enough, offside rear airbag not only badly out of shape but not even located on it's top spline mount. Replacement has arrived a.dyself and bro will have a go at it Thu, plus he has the software to set it up afterwards. Will let you all know how it goes....I might add that I'm saving up to buy the nearside replacement just in case.