group-line-format and Gmail - stop displaying [Gmail]

[davidandrewrogers]

Hi all
I use Gnus for email only.

To make small-screen usage easier, I'd like to get my Gnus group line to omit 
the square-bracketed word [Gmail]/ from the display.

I currently have

(setq gnus-group-line-format "%M%S%p%P%5y: %(%G%)%l %6,6~(cut 2)d\n")

but I can't find any clues about how to convert the group name (the %G above) 
into something that will eliminate the relevant (I mean irrelevant) :) part.

Even getting my group-line to not display "a set of square brackets and 
anything inside them" would be good enough, I expect - I don't have any other 
mailboxes with those as part of the name.

-- 
Thanks
David