I'd forgotten that Monday is Triathlon Club at the Goodwin pool - when they arrive the 2 remaining lanes become very congested. Last time I gave up but today I persevered and did nearly all of the routine.
The overall pace was good at 2:21min/100m over 2.5km, especially considering that I had a few slow lengths. I was able to counter these by a handful of lengths under 2:10min/100m. Across the session there was a clear loss of pace from an average of 2:13min/100m to 2:35min/100m linked to a n increase in stroke/length from 21 to 27. My arms felt tired and these data show that they weren't working well by the end.