what is this bird?? please ease my concerns..

Hello there everyone... I'm new to this but was wondering if someone could please clear my conscience...My girlfriend, my son and I were just leaving the house when we realised that a small bird had flew into the house. Because we had to be somewhere for 4.30 we decided to leave the bird where it was and then deal with it later. When we returned we found the bird on top of the light shade. It didn't seem distressed at our presence nor at being in doors, which led us to believe it was a pet that had escaped.  We tried to call the  the rspb, and a few bird rescue centres in our area but because, by this time, it was after 5 o clock, all lines were on answer machine. my girlfriend managed to contact the Rspca, who advised us to use a towel to catch it and then let it out through the door.

When we finally were able to gently catch the bird we did as advised, but I got the impression that the bird didn't want to leave my hands. It did eventually and flew outside and perched on a satellite dish next door. Again I got the impression that the bird did not want to be out in the cold. By this time it was around 6 in the evening, dark , cold and foggy outside. 

Looking back, I feel guilty that I had let the bird go, I feel I should have housed it in a box or something till the morning but that is just hindsjght I suppose.

So... here are a couple of pics I took of the bird before we let it out. I want to know if this bird is indeed a pet, to which I would feel terrible about letting it out, or is it a wild bird which thrives in this climate at this time of year. At which I would be safe in the knowledge that it would be able to survive the night and be ok  until tomorrow.

Thank you foor reading this, all help would be gratefully recieved.