Jane - yes the event at Sewerby Hall is an Old Time picking weekend, run by the Friends Of American Old Time Music And Dance.

It's not on the Foaotmad website - needs updating.
This is from a Foaotmad mailout:

SEWERBY Get Together May Day 2011

There have been some minor changes this year, mainly which the entrance into the park has been changed and the entrance now is through the EXIT gate onto High Sewerby Road, and not along the cliff top.

May Day weekend -
From Friday 29th of April to and including Monday 2nd of May. However as in the past we can move on to the park from noon Thursday 28th and do not have to be away until noon Tuesday 3rd.

September Weekend - From Friday 2nd of September to and including Sunday 4th. Again we can get on the park from noon on the Thursday and leave noon on the Monday.

More details contact John Yeaman johnthebanjo@johnthebanjo.karoo.co.uk