Traffic is non-existent? If only. Traffic is as bad now as it ever was, thanks in no small measure to expansion of the ridiculous 20 mph limits (Park Lane, Finchley Road, Southbank ... you name it, all 20 mph). No wonder average bus speeds have gone down in recent years, blamed in part on an increase in road traffic congestion.
All from the horse's mouth (TfL), in case you're wondering, at https://content.tfl.gov.uk/travel-in-london-2024-annual-overview-acc.pdf
Try driving in and out of London at any time of day and I guarantee you it's a solid hour plus.