PhD viva UK

Dear All, I would be grateful if you could clarify me some aspect of the PhD viva in the UK, please. Normally a student needs an external examiner and an internal one plus another one for the chair. Apparently for a Marie Curie PhD one needs two external examiners. So I guess the final commision will have two externals and one internal. Is that the case? Thanking you in advance, Salvatore