Mercian

“Mercian frame numbering consists of the number of the frame built that year followed by the year of manufacture, sometimes this system was reversed to have the year of manufacture first.”
“For instance 26876 would be the 268th frame built in 1976, so obviously your frame wasn’t built in 1933 or 1937, also there should be a single number near the main frame number denoting the builder of the frame.”