That question is difficult if not impossible to ascertain since figures for Chester are only published for those admitted to Chester Countess Hospital or which come within the Chester and West Council area. for e.g., on the 18th there were only and a daily increase of 4 and on the 19th that was recorded as 1 but increased to 5 on the 20th.
However, you do make a valid point since there must have been given the time period a cross boarder infection either through family visits, employment or shopping visits, in both directions.