Think I read on a newsletter that the 458/5s are going to run the Reading Road.Sooner or later.
Something like that anyway.(but your comment covers both bases)
458s will return to the Readings when the 707s arrive and displace them. I'm not sure what the final mix is going to be of 458s and 707s on the other Windsor Line services though. It appears that there will be some 10 car trains on Alton & Basingstoke trains too, I'd guess 458s as they are going to have First Class.