Teapot and milk jug - no makers mark, can you help me?

Hi everyone, I have a teapot and a milk jug that I was given from a great great aunt. I know that they were given to her by her aunt and they pre date 1950.

Teapot:
On the bottom has been printed
SHEFFIELD
PLATE
5
1640

and I presume the numbers are reorder numbers.

Milk jug:
No mark that I can discern other than a small G on the rim that touches the table.

Is anyone familiar with these marks and can tell me about the pieces or date them?

Kind regards,
Matt
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From the style and the lettering I would suggest late 19th - mid 20th century. They are, of course, not silver and the manufacturers obviously decided not to put their name on it so, unless someone recognises the actual pattern, I think that may be as far as we can go.

I should also add that it’s a coffee pot; tea pots are squatter and rounder.