Shed -- you make many points. Three comments.
1. Network Rail's capital fund is taxpayers money until the next ill-fated attempt to reprivatise NR. The TP funding is taxpayers money. The LHR project will be predominantly and possibly entirely air travellers money. So, no they are not competing for the same pot.
2. The 'pause' to the TP and MML project is caused as much by the inadequacy of the resources to prepare three major electrification projects simultaneously as by lack of funding. TP and MML are simply not ready to go.
3. The £147 bn. Of course even if we found the secret of eternal life we would never know the answer to the 'did it happen' question. We can't observe the counterfactual. It's the product of a model, the working of which will no doubt be scrutinised by Select Committees etc over the next few months.