@Everyone Thank you for correcting me that there were more than 1 possible 3 build combination(rare A Wal > Brest).
And as someone already pointed out the Northern part is possible(an anti German gambit)
The Wal>Bel[with French fleet] part:
Consider if to cement a game long alliance, and to test the willingness of the British to trust me, as France, I propose that England use the "3 build opening" on the condition that I can station a fleet in the channel for an extended period(say to 1903, or some specific build threshold), all convoys there will be handle by me, DMZ NAO, and no F Lon(A Lon is okay)
While initially France takes a build hit, it has superior position. If England reneges in S1901, it reverts to a Channel bounce opening. I have all the justification to build F Brest, and know where I stand with the British. If England blinks in A1901, well too bad for them, no F Lon, I can point to my convoy order and insist I kept my word, and want my reward, a garrison fleet in the channel.
I am not saying this isn't borderline impossible to achieve, but in the hands of imaginative people, it might just work. If you were England, and France comes TO YOU with this proposal, wouldn't you just want to try for the sake of its steer epicness. Some people consider English solo's to be on their to do list, maybe a 1901 3 build England should be one as well. Not saying that France won't just go ahead and stab England for London.