Looks like it dates from the Flanders Campaign of 1793 to 1795 

https://www.itv.com/news/2021-02-19/mass-grave-of-81-british-soldiers-uncovered-200-years-after-their-deaths-in-netherlands
Let's hope they receive the burial they deserve.
Strongly agree. Unlike, of course, the soldiers at Burgos that are still awaiting burial...
Almost certainly the brief winter campaign of 1794-95.