The Royal College of Music requires all international students to prove they can communicate in English. If you require a Student visa, the RCM is required to state on your CAS how you met the English language requirement for entry.
The RCM’s entry requirements currently comply with the minimum English levels set by UKVI for Student visa applications. For some courses, such as the MMus, the RCM's English language requirements are higher than the CEFR B2 level set by UKVI. UKVI regularly reviews the English requirements for Student visas, and in the event of any change, visa nationals will be required to meet both the RCM and UKVI minimum requirements to obtain a visa for their course.
The RCM is not permitted to issue you with a CAS until you have provided evidence that you meet the required standard for your course. Most students prove this by sending the RCM an IELTS certificate, or other acceptable language qualification, although there are some other ways to meet the requirements.
You should check the English language requirements for your course and accepted forms of evidence carefully.