See if you can get a rubbing of the raised mark that will let you read it--those things have tons of information if it's the actual registration mark. Sometimes fiddling with contrast on a digital image can help read it as well.

It is certainly a nice shape!

Google tells me that mark was used between 1891 and 1907.
The diamond shaped registry mark was discontinued mid 1880's and just the raised mark "Rd. XXXX" the XX representing a number. That mark is still found today.
The diamond shaped registry mark told what type of stuff it was...earthenware, wood metal etc....and the month, day and year it was registered. The newer regristration number, which would be on your pitcher would just give a number and you would have to look up a table to find out the year.
Nice pitcher!!

Rule of thumb...usually a mark listing a country of origin was after 1890 when the McKinley Tariff Act was enacted....but something might have been brought into this country by a traveller not sent as trade goods.

And after the turn of the century, the words "made in "often appeared.

That is the British registry number...it will tell you the year it was made....
Try putting a piece of paper over it and rubbing with the side of a pencil point...or a crayon.
But the fact that it says "Made in England" and has the registry number rather than the registry diamond tells me it we most likely made between 1885 and 1892.

With the design date code, it was designed in 1886, not necessarily the manufacture date.

Correct....that's the patent date...or registered date...
But the facts I mentioned earlier about not saying "made in England" and having the number and not the triangle indicate the time frame....are you telling me you were actually able to read that number? For 1886 it would be 40480 to 64580.

yes, I read the number.

Wow!!....good eyes!

Looks like it’s 539??, but it’s backwards.

R 53630 - try taking a snapshot at an angle and looking at it in a mirror as they look upside down and reversed.

Whatever...it's still 1896.