The Silmalloy Logo was registered in 1935 and came into use after that. It stopped being used when the box finish change about 1982. There should also be a logo on the end of the box which will also help date it.
Large Made in England came into use around 1928 ish and continued in use to the mid 1960's. This is has larger print and the lozenge or diamond is upright or read in the same way as the rest of the lettering.
The small Made in England came into use around 1966 following the Company changing hands and was used until the mid 1980's.
For illustrations of the logos please visit richardwheatleymuseum.org and look in the miscellany section.
Hope this all helps

