Pamela wrote:

Although RM provides confirmation of delivery, it doesn't seem to let you
track it through the delivery process using a courier's system.

RM offers untracked, signed-for but untracked, tracked and signed-for
options

I had a parcel sent from Australia which I could track but only as far as its
arrival in the UK, where the Aussie courier had arranged for RM to complete
the delivery.

I sent something to America recently, the RM tracking sight knew where
it was until it left heathrow, after that they directed you to the USPS
tracking site, once it had been delivered by USPS the RM site knew it
had been signed for.