Yeah Marcus was one of the British originals if you wish, at the same time as Alfie and Zoella and all the others. Niomi was his girlfriend but she joined youtube quite late.. he was already very popular at that point and part of the British gang, right when they started becoming very famous - I remember Niomi was in his vlogs and videos and then she joined in - so if you ask me, without him, she wouldn't have made it this far!! She gained a huge following at the beginning, like a few hundred thousand in the first few days because Marcus and all his youtube friends (Alfie, Zoe etc) were sharing her account.
Edit: To add, Marcus was like huge - they were always together everywhere - him, Alfie and Zoe, Tanya and Jim, Casper and Joe when he joined.