In those days there wouldn’t have been any electric pumps or swan-necks, and a lot more beer, especially in rural pubs, would have been dispensed by gravity. Nowadays we tend to associate gravity dispense and unsparklered handpumps with a fairly thin, shallow head, so you have to wonder whether they were doing something different in those days. Maybe it was a case of deliberately producing frothy pints just for the camera, but perhaps sparklers were more commonplace than we now think, or it could have been the usual practice to let the beer develop more condition, which can be done by a variation in cellar practice. It’s entirely possible to produce a thick, lasting head by gravity dispense from a newly-tapped cask.
It’s certainly my subjective impression that over the past forty years cask beer has tended, on average, to be served with less condition than it used to be, and you get a fair bit of beer that is not off as such, but just very flat and tired. Possibly the ending of the opportunity for a bit of hard-spiling offered by the afternoon break has something to do with it.
This brings to mind the North-East practice of “bankers”, which I have heard about but never actually seen. What this involved was serving a half into a pint glass and letting the head rise almost to the rim, then setting it on one side and, a few minutes later, carefully topping it up so the head protruded well above the top of the glass. Sometimes pubs would draw a whole row of these in anticipation of thirsty miners or steelworkers coming in at the end of their shift, which is where the name comes from. They might even put them in a fridge to keep them cool. I wonder if that still goes on. And was that technique once more common across the country?