These british Patent marks was used between 1842-1883. Between 1842-1867 was the first version and another version was done between 1868 1883.
This may help a bit. Top is number 1 below that is 2, left 3, right 4, Bottom 5. between 1842-67 1 - Class, 2 - Year, 3 - Month, 4 - day, 5 is Parcel number, bwtween 1868 - 83 Class is 1, day is 2, Parcel is 3, Year is 4, and Month is 5. I could not make out the letters on the pics, If you could get better shots or refernce the numbers, we can tell the date, down to the day it was made. Then a good pic of the whole plate may help us a bit too.
