Hiya, if you’re going to add lots of new buildings to places in the UK, please make sure to align the aerial imagery to the OSMUK Cadastral Parcels before you start editing. The imagery offset is around -4.13, -0.29m here, so you’re adding the buildings 4m in the wrong place. See https://wiki.openstreetmap.org/wiki/Good_practice#Align_aerial_imagery_before_tracing

Thanks