I know that applicants for the Cambridge LLM require a first class degree. However, I was wondering whether it is sufficient to have received a First Class degree only in your undergraduate/Bachelor‘s studies, or is it required to also have received a first class degree in your Master‘s studies, if such degree has already been completed?

Any advice is highly appreciated!

Usually the most important degree is your undergrad, so that will matter most. They won't overlook your LLM grade, but don't feel disadvantaged because of that. Normally, people use their good LLM grades to boost their 2:1 at undergraduate level but I don't think it works the other way around.