2 Merlins at the Bowl in Milton Keynes

I just saw two merlins descend and land at the Bowl in Milton Keynes.
A spotters group for cranfield said they were using callsign ‘buttercup’ I wondered if this callsign gives any indication as to what they were up to? The Bowl is an unusual place for them to land as far as im aware!
Any idea what they may of visited there for? They were on the ground for about 2mins each.