Britains Zoo animals are not named after Great Britain.
William Britain started making hollow-cast lead toy soldiers in 1893. The ranges widened and the lead Zoo animal moulds were used for injection moulded plastic when this process was perfected. The company still exists and makes farm models. It has been part of the Japanese TOMY toy company since 2011.
Britains models are widely collected and much information is available on-line - such as Britains Zoo (Britains Zoological Series), painted hollowcast zoo animals by W. Britain.
Most of those shown are quite late, not rare, and could be picked up on eBay for a few pounds.
This photo would cost me quite a bit of money to duplicate if I decided to re-purchase all 25 of the animals. Browsing Ebay.uk shows that all of the animals can be found for approximately 5-6 pounds each, plus double that as there is a significant cost for postage to Canada. It would cost me at least $500 Canadian for the 25 toy zoo animals in this photo. Yikes!
I have no shortage of animals in my collection (although most aren't really worth anything), but what I'd really like to learn more about are the zoo 'sets' that include exhibits. Something like this would be brilliant to own:
I had quite a few of these animals. I definitely had the giraffe, tapir, walking polar bear, tiger, lion, lion cubs, giant anteater, and llama. No idea what happened to them though.