Yep, you have a valid point there Entwood!
But is there some "rule" that pressurised vessels cannot be put into those ovens........you H&S and all that?

Pure H&S bull IMHO. 
If anything untoward happened to LPG tanks when they got a little warm would people put them in cars and then leave them in the sun?
Purely a case of "don't understand it, haven't risk assessed it, so won't touch it".
.. and based on the knuckle-draggedness of most LPGA "specialists" I would insist that, if the tank has to come out, it's done by the original fitter.
Kevin
I agree with Kevin....the tank wont explode if heated up.....even to quite a high temp....and i have been in some 'paint curing' ovens that have been set to quite a temp....coz its near the end of the day...and they wanna go home

Firstly, the max fill of a tank is around 70%, to allow for expansion, secondly, if the tank was overfilled, even say to 100% (Ive had this on a vectraC i owned, you could fill it to 100%, shut off 'float' was sticking) all that should happen if the lpg expanded, is the pressure relief valve should open and vent the lpg gas.
Tho probably, if you knew nowt about lpg, you might want the tank removed as well :-/