I wondered if anyone here might be able to help. My 17 year old did Grade 8 singing a while ago and wants to do a diploma - she thought ARSM. Her teacher has said she can't do it until she is mid 20s as the repertoire isn't suitable until then. It seems a bit off to me given the ARSM was clearly aimed at teenagers who have done Grade 8 but found DipABRSM with its viva a bit daunting and were defecting in droves to ATCL. Surely they should be assessing on how the candidate performs the music not on whether they have the voice of a mature opera singer or not.
For background she is an ex-cathedral chorister with a purer head voice and a warmer mezzo register and quite a lot of overlap between the two (so can produce a warm top G but her top Cs are more churchy). I can't help thinking that a careful choice of repertoire - oratorio/early opera/art song should be OK for ARSM. Failing that perhaps she could go down the ATCL route where you can select your own repertoire (although that programme does need to be mainly opera/art song but again with a bit of oratoria and early opera ought to be achieveable).
Otherwise are the exam boards saying that anyone can do any exam they are technically capable of except for singing where you need a fully developed adult voice?