My introduction to 'English' folk was initially in the latter 60s through Pentangle, probably Basket of Light, and Bert Jansch with his sampler lp. The attraction was obvious at the time: essentially melodic, and the prominent and bluesy/jazzy/virtuoso guitar work, with Pentangle adding the obvious nods to rockier elements, though this was significantly more the privilege of Fairport Convention.
I had missed out on Davy Graham's guitar breakthrough of the early/mid 60s which predates my introduction, and listening today to his album with Shirley Collins may well be the first time I have heard this. It is so simple and brilliant. Collins' vocal is pure but not folk-operatic, which I dislike, and Graham's blues and jazz infused style is stunning, making clear its influence in the work of Jansch and Renbourn. The current broad English folk renaissance has much to offer, and much to acknowledge in this seminal template.