Just a couple of examples of "routine" results.
1976 Womens Best Allrounder competition. Times taken over 3 distances, 25, 50 and 100 MILES. 25: 53.21 50: 1.51.30 100: 4.0.15, Average speed 26.665 miles per hour, that is 42.2++ kph
She won that
Her daughter Denise was 3rd in the same competition at 24.123 mph.
1975 July Goodmayes Wheelers 100 miles event, Open competition. 106 riders.
3rd place Beryl Burton 3.59.51. I do not know who the second woman was or where she placed, but the 10th person finished in 4.6.12 . She usually rode about 2.5 mph faster than the rest of the women. On this day the two men who beat her did pbs of 3.52.41 and 3.56.12. The next man did 4.1.15
Remember that these time trial courses were "out and home courses" so that winds and undulations generally got cancelled out.
I think at this time she was probably about 40 years of age.
Stay fixed. Keeping a cool head.