Thanks Nat and Borate,
Yes, it does coincide with a split, albeit only a split which occurred when I was cutting another track and did not lock the clip with the person reading the story.
I have tried splitting a "silent" bit as suggested and it does indeed create a click, where no click previously existed.
If anyone is happy to take a look, I have uploaded the whole thing as a zip here: https://stjamestrowbridge-my.sharepoint.com/:u:/g/personal/av_stjamestrowbridge_co_uk/ETVQ5FTWzk9ElnVcy-3ct_MBwPNt6hPFCiVvPNTViuG7Fg?e=A9TLEc
Or individual files here: https://stjamestrowbridge-my.sharepoint.com/:f:/g/personal/av_stjamestrowbridge_co_uk/EgXnA31_rMxAouj338YCPLABM88yCjJr7E-DONOKwcBCbw?e=AHWzso
I made this with version 8.91, but have just upgraded to 10.12 and the problem remains.
Thanks again,
Tom