Adrian wrote:

According to a leaflet its to do with possibly stopping 2 Amersham
trains per hour to allow 2 trains to run to Chesham instead throughout
the day thereby giving Chesham an "all day" service to central London.

Chesham already has an "all day" service to central London, although the
last leg of it is a shuttle from Chalfont & Latimer. Will they be running
a shuttle to Amersham instead?

Shuttle services are never popular with a public that like through services
and don't like spending ages on station platforms or relying on connections
that they don't information about until they reach the interchange. Since
they upped the Amersham service from 2 to 4 tph I guess they've had many
more passengers who don't know which is the Chesham train waiting for ages
who'd rather kill time further south (and not run up two hour limits on
Oyster).