Worked without any difficulty at all.
Not since conkeror died have I found something this useful for interacting with a browser!

Worth remarking that for emacs uses who prefer to work with text windows, emacsclient is a good alternative to opening a new terminal (the process suggested in the instructions here). This is because emacsclient will then place the text in a new buffer in an existing instance of emacs (the one running the so-called emacs server) so you can for instance easily transfer text between buffers.

My config therefore says ["emacsclient", "+%l:%c"] and it worked the first time. Bravo, Lebon! Un nom tres adequat.