Tom Anderson wrote:

Not that i'm complaining - more smaller islands means more
coastline, which i hope will be constructed as ecologically vital
saltmarsh.

Unless they invent a new engine which is birdproof, I think not.

Would Crossrail trains run through to the airport?

Good thinking - I'd say so.

And what happens on the Essex side? A connection to one of the
existing Southend stations? Somehow connecting to Stansted - two
sides of a triangle via Stratford, or some new line running along the
M25/M11 to join the existing line at Harlow?

NIOL [Not In Our Lifetimes].