That seems very likely - if so, it's one hell of an infestation - there are thousands of these and no normal acorns. There are thousands of Quercus Cerris n Cornwall, it's thought they were commonly planted to harvest as pit props as they are quicker growing than Petraea or Robur.
I seem to have seen loads more than usual this year. Maybe I have been looking out for them more since Custards thread last August?
I remember someone showing me pignuts years ago and being a bit startled as they started appearing all around me once I knew what to look for.