Point taken Larry, but I got a handful of other shots at the same time, and all show the bill as on this one. As it happens, it's only in the last few days that I've got round to looking at them properly. Anyway, regarding the size and shape, it's good to know it's not just me.
I should add here that this was one of two birds, and our attention was first drawn to them when we heard crossbill flight calls, albeit rather unusual-sounding ones (this being commented upon at the time). We had a sound recorder running, and it managed to pick the calls up. See
https://www.xeno-canto.org/504233
The problem is that as well as sounding quite unusual for Common, they aren't really like typical Parrot either(?). Then again, we can't even be absolutely certain that the calls were emanating from the bird in the pic.