Looks like you have obtained all the DVLA info on the cars apart from the last known keepers. Trouble is Not all scrap yards back in the day told the DVLA that they broke up/scrapped cars as they should have which left a lot of the records wrong. Just because its not shown as scrapped means it hasn't been. Also it maybe sitting in a barn/garage waiting to be found after Mrs Miggins or her husband died and the estate is going through Probate and the likes
