Thank you all for your replies, all of them interesting and useful answers. Firstly, to Peter’s answer refering to the article on the Kiev ship in May 2010 issue of MB. Whilst I buy MB fairly often I did not happen to buy the May issue, I have just been now to check through my collection and found I don’t have it. As a non-subscriber I probably won’t be able to see the article on-line either. But how brilliant that someone has dealt so recently with the problem I raised.

 Neil’s suggestion of using a compass cutter is the one I’m going to try out. As it happens, today, which is the day after I posted my query, I thought of a compass cutter during an idle moment in work, and I have one in my tool box. What I’ve done is cut a round template from cardboard, and then cut it’s inside out to the right diameter so that it looks like a ring. Then I cut out a second circle which is 2mm less in diameter than the inside of the first circle, for that is the width I want for the helipad roundel. By placing the smaller circle inside the larger one, directly in the middle so that it has a 2 mm gap all round between them. Tack them down to where I want them on the ship’s flight deck, and then use a paint brush with white paint to paint the gap between the two circles. Then after two or three coats of paint and leaving it to dry, I lift the cardboard templates and hey presto I should have a white roundel on the deck. I haven’t tried out the painting yet, but the cardboard templates have been made and they are good. I’ll let you know how i got on.