Can anyone identify these bricks, which I suspect are LEGO clones. They may be more than 30 years old.
I bought them on ebay as Betta Bilda from LEGO/Duplo dealer. Some BB was included, but these are unknown to me, with an extensive BB collection.
The underside of the bricks is hollow and with apparently random numbers - they aren't part numbers because they are different for the same part and sometimes the same for different parts. Window frames have no top studs.
I took a good look through many posts with similar questions, but found nothing that matched. Many Google reverse images searches kept pointing at real LEGO/Duplo, before I noticed this place.
Usually I can identify unknowns like this, but these are a real challenge.
Edit (Nov 29, 2019)
Some comments have asked for clarity on size of these bricks. The majority are close to if not identical to 8 stud LEGO, although there are also 2 and 4 stud bricks too. They clip to Betta Bilda pieces, in a similar way to authentic LEGO. The window frames appear to be confirmed by two comments as 1950-60 LEGO, but additional insight would still be appreciated.