The Newbury conditions were probably 10mi better than the Nationals at ECCA that year but there was definitely still an aspect of fatigue. I went out much harder in the Newbury and hung on pretty well whereas I was running on fumes (mental and physical) at the Nationals.
I reckoned it was 5 miles better, based on what I did, but that kind of ballpark. You were flying that day at the Newbury, looked significantly faster than topham at the end (he passed me around the same time)
ISTR you overtook me a bit earlier in the day when you'd already done the 24