Interesting post from John Bolton on Facebook..
“My interest is the history of Wellingborough Foundry which I have been researching for several years. Identifying the Block and Head Castings made at Wellingborough ("W" Logo in a diamond) has led me to understand the castings produced at the various other Foundries that produced for BMC/BL. There is a lot of misinformation online such as the "M" in incomplete diamond being somehow related to Wellingborough when in fact it stood for Morris and was used by the main Morris Foundry at Engines Branch Courthouse Green Coventry of which Wellingborough was a branch.
There has been recent discussion about Date Codes which came in 3 formats for various A Series Blocks and Heads:
Day, Month
Day, Month, Year
Initial character, Day, Month, Year
Attached is the Standard introduced by BMC 1953 reissued 1971.
The occasional references to "Batch" for the first character in various Forums confuses the issue. The idea of batch would have no relevance to Wellingborough Foundry where I know the production process in detail. As the Standards says, Batch or Day and certainly it was Day that was used. The other possibilty is Shift but Wellingborough only had one main production shift (Maintenance had 24 hour a day split into 3 shifts, there was some night shift in the 60s but mainly Core making). Coventry Foundry, Courthouse Green may have had more than one shift but yet to be confirmed.
It is important to understand that Date Codes and other Codes were for the purpose of this US Standard and for the purposes of Inspection to trace back defects to eliminate whatever was causing the defect. One of the key measures of the Foundry was "scrappage" due to its impact on profitability and so important that at Wellingborough there was a daily morning "Scrappage" meeting attended by senior Managers and Inspection to review identified rejected castings at the Foundry and by the Customers (Coventry, Cowley, Longbridge, Abingdon, Bathgate etc) and to action solutions.
I will be posting my research into Logos and Codes for the A Series next year and hoping members can help fill any gaps.”