Thanks for all the sdvice, chaps. On my old Citroen CX I could have put suspension on tip toe and driven it out. You could be right Al, load rear LH corner with fat old ladies, but not many about here. Back in 2009 I filled the boot of my 2003 ex-plod 3.2 with typemetal pigs in the icy winter, refuelled the car and both rear springs broke; so I was cautious of loading the LH corner.
I sought advice from my son's builder and he sent me home with an Acro prop to lift the car up with. But that meant me getting into the pit to put it into position, which looked tricky.
I wondered if I could jack the car up from garage floor level. I could not get my trolley jack under the RH rear jacking point. Bother. Needed a slimmer jack. Then had happy thought - use the car jack. Car jack went easily into jacking point; jacked car up until I could get trolley jack on three pit planks under RH beam; jacked car RH side until I could put planks under front wheel; job done!
Car seems undamaged, exhaust not banging - lucky me.
https://www.dropbox.com/s/9jr8bd8ycaggk74/carINpit50%25.JPG?dl=0