Sorry for no earlier reply -- I had a lot of jobs today!

Anyway, your hunch was brilliant -- it was exactly that! I tried modifying the default profile 1 and after that there was no looking back. Thanks so much!

For your amusement the reason the profile is called Gutter-Profile is because the Observatory is called the Guttter, after an Oscar Wilde quotation: "We are all in the gutter, but some of us are looking at the stars", which is inscribed on one of the roof support beams.

Thanks,
Richard