water dripping off felt inside roof?

May be of use
http://www.projects.toolvolt.co.uk/listing.php?id=001

But make sure the vents are clear in the soffit and that thay do go right throu into loft and not there just for decoration.

If you have small round vents in your soffit that are right throu, then increase the amount, manufactures recommend every 200mm all the way round. Which equates to a 20mm slot vent all the way round.

If you have a high pitch roof, fit 2 tiles two thirds the way up on all sides of the roof.

www.toolvolt.co.uk
February 2010

when was your house built as many roofs in the 70s used a bitumen based material as felt this material sweats its the warm air from the home comming up to the cold air in the loft and condensation is formed you can cut in sofit vents in the soffits or a couple of tile vents this should prevent the problem

wegs
January 2010