As I recall, flying the Yellow Jack was not the sole privilege of Plague Ships such as yours but rather a routine hoist meaning 'I am inbound from foreign and (therefore) require Customs and medical clearance' (and probably may be still ... Jack?). I'm bound to think that sea travel with its attendant incubation period was a good pandemic-blocker, now lost to us as we saw with the jet-hopping Severe Acute Respiratory Syndrome which was so fortunately nipped in the bud not so long ago.
I suppose that your entry to the Mersey was seen by the port Medical Officer of Health as his finest hour, and he was determined to save the Nation at whatever cost to the 4999 on board .... your recall of the very swift Customs clearance has made my day (some distant progenitors of mine were Preventive Officers in the halcyon days of that once-great port; I feel quite confident that, had they been faced with such circumstances, their discretion would have supplanted their valour with no difficulty at all).
Danny, after so extended a stint in India flipping between very-wet-and-warm and very-hot-and-dry, did the return to British weather come as a relief, or otherwise? I wonder if the first, so-long-anticipated pint was something of an anticlimax, and whether the battered state of Liverpool amidst the general conditions of shabbiness and shortage came as anything of a shock to those returning?