OK that sounds strange. As us crew have been told that strollers should be brought up to the aircraft door if they have been correctly tagged and put into the right hold!!
I do however know that some teething problems were being had at LHR and that at LGW it is definately not happening.
As I said on the big aircraft as long as there are not loads and loads of strollers, they usually have room onboard. Even on the smaller aircraft, if it is not full, we will try and put it onboard for you. So don't worry. I think you will get your stroller at LHR. Just make sure you tell the ORD gate staff and the crew as you get on and explain how important it is to you, it should be fine.