If you want confirmation, the easiest bits to "check" are Aylesbury and Coventry. London and Birmingham are too big for the features to stand out.
Here is the official HS2 map: https://www.hs2.org.uk/map/?mapView=9_52.0744_-1.8347
HS2 benefits pretty my everyone along it’s route path through increases local services as capacity is released from the current lines
Midland Connect have a good overview of what it enables them to do – https://www.midlandsconnect.uk/media/1602/hs2-released-capac...
There’s also a document somewhere that covers how HS2 increases short distance services from Euston somewhere
Local rail transport should benefit hugely from HS2
It’s happened often enough that it’s a wink and a nod that nothing was found. Foremen and anyone ‘in-charge’ will not be on site until any kind of digging is complete.