O' level or A'level eng lan test allowd?-pls help

[mahfuza49+]

Hi Forum friends,

My Tier 1 (General) adult dependent son who is now 22+ ( he was 17+ when issued entry from our country) will apply for ILR at the same time of mine. He is studying Mechanical Engineering at the University of Manchester and in the final year now. He did his GCSE O level and A level from our country under British council; so why he didn't require any english language test like IELTS or something like that while he got the undergraduate admission as required for the overseas student. Since he hasn't still finish his graduation - can't show his certificate as a english language requirement.

I would like to know:
Can he use his 'O' Level ( where he had english papers) or A level certificate as these were done in English medium and under British council with Edexcel syllabus?
or otherwise I have to ask my son appear for B1.

He has done his Life in the Uk test.

Please friends reply me from your knowledge and experiences.

Thanks you all in advance.
Mahfuza