Hi Robert
Charr can legally be caught in the Cumbrian lakes Lancs Lad names but please refer to the Regional EA byelaws for close seasons and methods (especially bait byelaw 18) before having a go.
The lake Ron remembers Hugh F-W blanking on was Coniston. Trevor, the Coniston coal man saved the day by bring Hugh some Charr from his freezer for the Charfest!
Also, re introduction, refer to s.30 of the Salmon and Freshwater Fisheries Act 1975. Best advice - don't do it!
Just to tempt you, I've attached a pic of a cock Ennerdale Charr taken for broodstock and subsequent conservation re-stocking.