Followed?

When I was away for those few days recently, I frequently had the strange feeling that I was being followed.

Despite using all the old MI5 tricks, stopping to tie up my already tight shoelaces, peering at reflections in shop windows and car mirrors, turning abruptly and walking back the way I had come and sitting at park benches with a small hole cut through my copy of The Times, I couldn't spot him anywhere.

Then, when I turned suddenly and still failed to see anyone unexpected, I heard the sound of a small, distant splash...