[CdM] Speaking only for myself; I'm too lazy to program it.

Anyway, did some more work on this today, and spotted an interesting complementary move to my Friday's suggestion.

Alperton->Kensal Green->St John's Wood->Mornington Cresent. This is just a straight horizontal. But curiously in the complex plane the sequence has five components

.. not four, because it cuts the Metropolitan line between Finchley Road and Baker Street.

Anyway, I'm still looking, though.

[CdM] Well, I've got 347 stations in my database including N.L.L. and ghosts - and that doesn't yet have the old Met line stations to Brill - nor the Southend branch, nor some of the old District line stations. Memo: Must update database ! : So say there are 380 stations all told - then as you say, as (M=0) = Alperton by definition, and (M=4) = M.Cresc, again by definition, then we only need to calculate M1,M2 and M3 i.e. 380 x 379 x 378, just 54,439,560 possible combinations. But of course that is without taking into account LV, token placings, Becks variance, Transient moduli etc. etc. It would be naïve in the extreme to think that the four-station solution would work under just any old set of initial conditions. So, let's hypothesise that about 0.1% of possible initial condition combinations will allow the required result then the figure of 54 million needs multiply be 1000 to 54 billion. This may take a bit of processing after all - as the initial conditions will have to be set up each time. I think we're back to skill, I'm afraid.

The more calculations are carried out I am sure it will end up staring us in the face. I have been struck by the elegant simpicity of a the General Theory of Relevance: where e=mc².( e being Euston)
I disagree with this in one aspect and the is the appropriatness of the mc² given the Euston conflagration. The more sensible move and theory is e²=mc, (e being Euston Square) thus avoiding inverse coefficient of the magnetic modulus of previous BR station.
This brings me neatly to what may to some be a moment of de jvu. I question at this stage about Alperton as a first move and propose the usage of

rabmc²

where
r=Ravenscourt Park: a=Alperton: b=Blackhorse Road : with the ²on the diagonal being Euston Square. Geometrically this three sided quadrilateral could work in parallell to a divergence of LV on the Jubilee Line.

I proved all this ages ago with a Fronsky diagram drawn on a napkin. It was far too trivial for me to bother reproducing it here.