Kerry, the other sizes they've added are those that are still in regular production as documented in the master product list posted on the Ilford website, just not normally imported to the US.
Originally Posted by kthalmann
I had asked Ilford USA whether they could supply any 2.25x3.25 HP5 Plus, and the answer was that it's not regularly imported into the US, but they would look into the possibility of bringing in some as part of the special offer. I'm sure they got other requests as well. And then they actually delivered by expanding the offer in this way. I'm really pleased - looks like they're trying hard to be responsive. Perhaps they can add 4x10 next time.