
Dating from 1930 the Neopost machine was a six value model (8 values introduced in 1952). The breaks in the bottom line either side of the value indicates that values were interchangeable (a solid line indicated a fixed value and thus a separate die for each value). Your meter mark dates from 1936 onward ... this model was not superseded until 1964.
All GB meter marks had the country name which is different to adhesive stamps