l have just bought this car but have heard a rumour that automatic gearboxes are likely to fail.My question is can l stop this happening, and what shall l look out for - are there any tell tale signs.The mileage is 85000.Thank you

Just drive sensibly and service your car regulary. You could have your gearbox oil changed. But its more likely to happen after the 100,000 mark.

l had a megane 2.00 coupe import 'R' reg never had a gear box problem or anything major, only the speed cable stopped working and l clocked up about 8k miles before getting it fixed had a better price for it too!!! cost about £40

The biggest single reason why any auto box would fail is, poor maintenance. Automatic transmission fluid not only lubricates the gear box, it transfers the power from the engine to the wheels.
Automatic transmission fluid should be a bright clear cherry red colour, if its not then its time to change the fluid.
Many people make a big mistake with a transmission fluid change, they forget to change the gear box fluid filter.
To remove the filter u need to remove the sump from the gear box, inside the box u will find the filter.
Ja.

Should not be a problem so long as serviced properly and regularly

Solve the problem by not driving French Junk!!

By 85,000 miles any damage might well already have been done. All you can do is have the fluid changed, with the filter, and do not abuse the gearbox, i.e. do not change from N to D or back again until the car is stopped, do not select reverse till the car is stopped, do not leave it in D if you're stopped for any length of time, and try not to gun it away from the lights. Common sense if you've been driving an auto for a while.