There is a difference between extending a couple of platforms to take the occational charter trains and redesigning the whole thing to accomodate them. This year the regular charters have run on Sundays where they don't interfere with the service. With the improvements proposed it should meet its designed 2thp service requirement more consitently than it has been doing without being double track all the way. Time wil tell.
I wasn't suggesting doubling throughout, only enough to allow for out of course delays and sufficient signalling to allow for an occasional charter without disruption.