Within the past couple of months I KNOW ! came across a reference 'somewhere' concerning "Barge Registration Numbers" - that they were some sort of 'Public Health Registers' set up around the 1880s that permitted Local Authorities to inspect - and trace if necessary - any inland-waterway Trading Vessels to ensure compliance with the then-equivalent of Health & Safety Regulations. [This came as news to me, as I'd always believed them to be more the equivalent of Annual Licences.] "They are held in the Birmingham archives up the spiral staircase."