Britton led the chasing group, which eventually came down to herself, Britain's Jessica Coulson and Portugal's Sara Moreira. Coulson broke free over the last 1,000m to finish third in 25.42, six seconds clear of Britton (25.48), with Moreira fifth in 25.51.
Coulson and Moreira will be among Britton's rivals when she defends her European title in Budapest next month. Ava Hutchinson (DSD) was the second Irish woman home (ninth), followed by Sarah McCormack (Clonliffe) in 13th and Kerry Harty (Newcastle) in 21st.
Ethiopia's defending world cross-country champion Imane Merga (28.07) won the men's race, two seconds clear of Kenya's Vincent Chepkok. David McCarthy finished in 18th place (29.20), followed by Portlaoise's Michael Mulhare (25th), Kilkenny's Brian Maher (40th) and Annadale's Eddie McGinley (53rd).