Tim Roll-Pickering wrote:
If a Liverpool Street to New Crosses root is needed, restoring through
services on the connection at St. Mary's would do the trick better, if the
District and H&C could handle it.

They can't. There is literally no capacity for additional movements
across the Aldgate triangle, which means that any new services via the
St. Mary's Curve would have to be diverted away from the District main
line, increasing overcrowding. Likewise, Aldgate East would be strained
with all of the new interchanging traffic (St. Mary's station is long
gone and will not come back, no matter what).

A far better option is to rebuild Whitechapel DR to increase and
rationalize track capacity, and to additionally reconstruct the station
to provide more and step-free access between the two routes.