Lonely Heart addresses probably the last possible gap on the Great Slab, between Jugged Hair and Art Brut. The climbing is around Font 7b (V8), with a very high crux. Heason has graded it E9 6c.
On the same day Ben also soloed every other route (except for Toy Boy, Ron Fawcett's E7 7a) on the Great slab:-
“Synopsis” E2 5c, “The Great Slab” E3 5b, “Parting Hare” E3 5b, “Hairless Heart” E5 5c, “Heartless Hair” E5 6a, “Artless” E5 6b, “Hairy Heart” E6 6a, “Jugged Hair”, E6 6a, and “Art Brut” E7 6b.