There is a proposition that Alperton to Mornington Crescent can be achieved in four moves. However proof has not been accepted for the existance of this number.
Valid point Artaud, initial formulas have found that we do require non-zero LV for the (move=1) station, and we will somehow need to equate these cofactors into the Fronsky calculations already mentioned by Blob. The analysis by Blob is showing that the next move in avoiding the Circle line has put a strong emphasis on 'allowance of linear movement' so I agree Euston is unwise. My own extrapolations suggest we should focus on either Leyton or Loughton thus avoiding divisibile cardinal notation.
I've had a cursory look at this and have found one flawed real-world solution and one ideal-world solution that only works in complex MC phase space. The Real solution is Alperton->Acton Town->Aldgate East->Moorgate->Mornington Crescent. The Imaginary solution is Alperton->Aldgate->Moorgate->Mornington Cresent. Unfortunately this is an odd-even move movement mapping which it is trivial to prove is irreconcilable. So you can cross that solution of your list as well. But this is only a first-pass approximation. It may be possible to use a one-move Expansion on the Imaginary at thereby unite the two. The trick, of course, is to do this without forcing a Real/Complex bifurcation.
OTOH, if you can acheive it /with/ an Re/Im bifurcation, then it's been proved that a true real-only analogue move to the bifurcated move does exist - if only it can be found. Which is the most tantalising thing about this puzzle. Theorists are almost certain it /can/ be solved rigorously, but no-one has ever been able to prove it.