Crockett & Jones last 240 v. last 345

[Kawini]

Good afternoon gentlemen.

I have a pair of C & J derbies built on Last 240 which fit me perfectly. They are branded Peal & Co. so come in size US 10.5D.

Can someone tell me if a shoe built on Last 345 will fit pretty much the same way. My bit of concern arises because - as I understand it - Last 345 only comes in widths E and G. I am eyeing a pair of shoes on Last 345 in size US 10.5E.

Any thoughts on relative fits of these two C & J Lasts.

Thanks very much in advance.