Just goes to show how much scarcer these are nowadays compared to twenty years ago. I have seen quite a few threads on here or other photography / wildlife sites where people are asking for confirmation of a House Spadger's identity.
Spanish Sparrow's are very rare visitors to the UK and I believe it isn't actually very common in Spain either. It's mainly found in the very South and East of mainland Europe. It does look very similar to a House Sparrow though but has lots of dark streaks on its underside and a white ( instead of grey ) cheekpatch.