It's certainly not difficult to apply directly to the big tech players - you can find these pretty easily with '<company name> uk careers' Google searches:
I don't really have any experience applying to mid-range companies, but intuitively it doesn't feel right that anyone should feel the need to conceal their identity when searching for a developer role, especially if your friend is experienced enough to be optimising salary rather than worrying about getting a job at all. Are you sure there hasn't been a misunderstanding?