Thank you, that worked beautifully on a test piece but on the target document it made it non-responding, threw up an error after a minute or two and ALL the text was in caps. Clearly a problem with the size of the document, not your code so thank you for answering my query but I seem to be asking it to do too much on a huge document. (4,000 pages, 1/2 million words or so!)

However, since it works on a smaller document I can still use it. I'll just copy chunks of text to a new document, run this macro over that and then re-paste the altered text back into the huge document. That should work. :-)

Many thanks for your help, it is much appreciated.