All our toms are smaller plants this year, both in the GH and outside...
We always grow Shirley, (and a couple of other types), and even with pots full of Jack's Magic, (with peat, and well-watered several times a day if necessary), they're thriving on just two trusses per plant - maybe three in the GH, but I've never known the crop to be so awkward as this year!
However, because these trusses are reduced, the size of the toms is pretty good, and luckily, as we grow well over forty plants everywhere, the overall yield will be OK, but I can't fully understand why during this year they seem to have stalled!
I do think that during the ferocious heat we had in June they decided to buckle down, and get the hump, and this has something to do with it, but also there's a dearth of sideshoots too, so we'll see in a couple of weeks what the crop looks like, but has anyone else experienced this?