And the only way MAN could get a 2nd runway was to have it positioned as it is so as to minimise the use of greenfield sites and so getting grudgingly approved by Cheshire Council.
Not grudgingly approved by Cheshire East who opposed it but endorsed after a 100 day planning enquiry.
And of course the northern option would have meant a realignment of the M56 junction, made very difficult by the need for sufficient taxiways at the correct levels to connect to the terminal area, the complete demolition of T2 and the cargo area as it would have been in the Public Safety Zone, the exposure of a large new population to aircraft noise, particularly Wythenshawe and the removal of the Girl Guides Camp in Ashley...
And as has been pointed out, the constraint would still be departure routes, so not a really appropriate use of resources. Apart from that Council Van, any other ideas...
If the Airport had chosen anything other than the option that was originally built, it would probably still be a single runway airport as planning permission could not have been realistically obtained for any of the other options.