I noticed the high number of performers as well. The choreography is what I would expect from North West morris, though faster and more fluid (probably because the dancers are younger).

The event is a Rose Queen - I remember them from when I was a little girl. The same as a May Queen, but usually held in June when the weather is a bit better. A local girl gets crowned as queen and bands and dancers, etc. all get involved.

Do you have anything similar?