Kingfishers on the River Blackwater

I saw a pair of kingfishers (Alcedo atthis) this afternoon as I was walking alongside the river Blackwater between Frimley and Farnborough.  They were chasing each other up and down the river, occasionally alighting on the branches of overhanging trees, and then dashing off again, making strident cheep-cheep calls all the time.  While I have regularly seen kingfishers on this stretch of river and on the nearby lakes, this is the first time that I have ever seen two of them together.   It was also the best view I have ever had of any of these birds: before today I had only caught glimpses of a flash of blue disappearing into the distance, but this time I got a clear views as they raced past. They didn't seem to notice me.  I presume they were performing the courtship chase, mentioned in BWP-CE, though September does seem an odd time of year for courtship.  However, whatever they were doing, they certainly seemed to be enjoying themselves.