A further snippet from the same era is that during WWII there was of course much Royal Naval activity at Liverpool, in addition to the merchant trade which was operating at full capacity and more.
Unusually, it was decided to appoint a King's Harbour Master at Liverpool, an office normally held only at the RN Dockyard Ports such as Portsmouth, Plymouth, Rosyth etc. Selected to fulfil this role was Pilot Tom Small (born 1873 and who had retired in 1938 aged 65.) Such were the merits of Tom Small (a Blue Funnel pilot for more than 30 years) that he was called from retirement for the role ; and he it was who identified, organised and designated the many anchorages as shown on Barney Sale's DORA chart.
Quite how well the the red circles served would depend, of course, on the navigational skills of pilots and others in identifying and adhering to the designated/plotted positions; but the evidence of effort and organisation is clear in any event.
My father often told me that, so closely were the ships crowded into the anchorages at the time that the need to maintain anchor-watches was particularly acute and any sleep or rest was at a premium. As he expressed it, "Trousers became worn through at the knees through kneeling on settees and peering through portholes to make sure that anchor bearings had not changed , anchors had not dragged in the tideway and ships had not become dangerously close to each other."
Tom Small had two sons WJ (Bill) born 1902 who became Master of No. 4 Pilot Boat and OG (Overton or Ovey) who served as a Blue Funnel Pilot from 1939 until his retirement in 1965.
BY