It's hypericum 'Hidcote', (one of the St John's Worts), yes. The cobweb may be incidental, it could be spiders webs, but it may be a caterpillar of one of the moths. There is a blight that affects hypericum, but it tends to start low down, and the whole plant is affected (and dies!). However, re the browning off like that, I stand to be corrected, but it looks as though that's mainly one branch. There's still a lot of green about. There's no damage low down on one part of the shrub, is there?

eeww that doesn't sound great. such a shame, it looked so nice for a few weeks.

I'd give it a hard prune and water well . it may well recover.

Pruning done, so lets wait and see. Thanks.