Brittiläisellä
Brittiläisellä is the adessive case of the Finnish word "brittiläinen," which translates to "British." In Finnish grammar, the adessive case is used to indicate location, possession, or the means by which something is done. Therefore, "brittiläisellä" would be used in sentences to convey concepts related to "on the British" or "with the British" or "by the British."
For example, if one were discussing a tradition that originates from Britain, they might say "Se on