[Tim Grabham]

Many thanks for your reply. I am not sure this was the issue as none of the clips had any colour correction applied to them.
But another user has offered a solution which has worked and that was to ‘Try Unchecking Hardware accelerated decoding under Preferences > Media > Enable Hardware accelerated decoding.’
This worked a treat and so I don’t seem to have the issue any more.
Thanks again for your reply, I very much appreciate the support of these forums.
Tim