Most of the opportunities in and around Edinburgh were covered in the initial ELR proposal in 2007. However, a tram line was subsequently built which included the section from Haymarket to Edinburgh Airport and the Waverley line re-opened, both of which had an impact on the original ELR model and resulted in a number of changes being made to what is now the 2016 version of the ELR proposal.
Another route which in reality should have been a very important link for consideration was a line to Penicuik via Auchendinny. Unfortunately Waverley Court in Bonnyrigg is built on the old railway formation as it approaches the B704 and in general a new railway using the old route does not seem all that doable because of this impediment. Even with the Waverley line reopened and the new Eskbank Station moved further south than the original one, a spur to Bonnyrigg could be facilitated basically on the old railway formation and would involve a bridge over the A7. As shown on the 2007 ELR proposal a short spur to Dalkeith could be incorporated. The old line to Balerno was looked at and although there is a lot of housing near to the route it is difficult to envisage how reinstatement of this particular corridor would achieve a positive outcome.
Another link covered in the 2007 ELR proposal was a spur to Pinkhill (Corstorphine) from Balgreen which was again abandoned because of the tram line. However, I have suggested in the paper on the ELR today in 2016 (Item 5) that this could in fact be a tram spur, as well as suggesting an extension of the tram line to the foot of Leith Walk and a spur along London Road to Meadowbank.
It is interesting to note that when the heavy rail Dalmeny Chord proposal was dropped in 2012 (see Map 1.1 (2016) , it appears that what seemed a very sensible development which would have allowed Glasgow to Edinburgh trains to avoid the often problematic Winchburgh tunnel and stop at the now open Edinburgh Gateway station, was in fact a very realistic development. I suspect that the Edinburgh to Glasgow mainline electrification programme dealt the Dalmeny Chord the final blow, because it would have meant this being electrified as well. Swings and roundabouts you may suppose but in the greater scheme of things, perhaps a missed opportunity.