Mothercare Citilite and Graco Citisport (they are essentially the same pushchair) both fold squarish, so they are much shorter than a folded Volo but also wider. The seat is quite narrow though so if you have quite a big child I would recommend trying it out for size first.
I've the compact they do go small in length, think they were designed to fit the back of the mini or something but Silver Cross have replaced them with the 3D. They are pretty awkward to fold (once you get the hang of it it's not too bad just don't let anyone else do it without a half hour lesson in what to do) and it doesn't stay shut well if you have the hood attached. Otherwise it is pretty good as small travel system.
Was it? (didnt look like a zapp atall). Thiking back, I think I prob saw it when in there with my pg friend, whose baby is now 7 months I knew you'd know!! BTW, did I let you know the star light arrived safely? Sorry if I forgot to.