This annual event invites teams from the four home countries as well as Ireland, with England hosting it this year at Aintree Racecourse.
Although the course was flat, the long, tufty grass and boggy patches made for energy-sapping racing.
The women raced over 6k, taking in three laps of the spectator-friendly course and conditions were near-perfect with little wind to hinder the athletes.
Both athletes got their call-up from the England selectors on the back of fine performances throughout the year.
Williamson, 59, making an impressive tenth consecutive appearance in these championships, showed she still had international pedigree despite being in the final year of her age group, securing gold for the W55 team.
She ran an intelligent, even-paced race and worked through the field, overtaking competitors on the last lap to finish in a time of 24min 33sec in an age category won by England’s Clare Elms in 22:31.
Edwards was making her debut England appearance in these championships and fully justified her selection, coming in as third scorer for the winning W40 team and a hugely impressive tenth place in the overall race in 22:08.
She said after the race that she had been apprehensive beforehand but was very pleased with her run and delighted to claim a gold medal for the England team.
“I had a storming run and am delighted to have made the top ten,” she said. “ I only missed out on an individual bronze medal by ten seconds.”
The overall race winner was W40 Kirsty Longley of England in 21:00.
Both Williamson and Edwards have a full schedule of winter racing ahead as they target an appearance in the BMAF Championships in Wales in March.