Hello Vladimir,
Sorry I remembered your name wrongly, and referred to you as Vasily in the thank-you message I sent round a minute ago.
Doing too many things too quickly - please forgive me!
Many thanks for your suggestion, which was the one I ended up using.
Cheers
John
Dr. JW Faithfull
Curator in Geology
Hunterian Museum
University of Glasgow
Glasgow G12 8QQ
Scotland