Well to my knowledge, there are quite a few Georgian/Victorian era homes still knocking about in the UK, especially Victorian terrace homes found in large cities especially. Looking round Portsmouth, it looks like there are quite a few renovated Victorian homes. However worth noting parts of Portsmouth were bombed in WW2 so many house are likely to be post 1950s and the area where tornado is supposed to have gone through (Old Portsmouth - Southsea Common) looks to be lots of greenspace right now. I would say its entirely possible that some of these types of houses would still be standing given other housing of this era around where the tornado was suposed to have gone through, albeit with renovations (specifically to roof structures) so maybe we wouldn't get the best idea of construction quality, so its quite hard to say - not really an answer to your question!
Is it possible that the brick homes seen today in that area of Portsmouth are the same type of homes there in 1810, or is that unlikely? There's a frustrating lack of detail with that one, despite it being the most recent, relatively speaking.