@StressIsMyFuel
I'm so, so sorry to hear your news.
Here's the Royal Marsden NHS second opinion page:
https://www.royalmarsden.nhs.uk/about-royal-marsden/access-policy
They say this (NHS):
How do we manage second opinion requests?
Due to the high number of second opinion requests The Royal Marsden receives, we are not able to accept all referrals for a second opinion. To avoid delays, for all NHS second opinion requests, please aim to keep the referral information to a maximum of 10 pages which should include the following information:
- Referral letter
- Last hospital letter from local oncologist, surgeon or other specialist
- Relevant scan reports
- Histopathology report
Where the referral is accepted, a clinician will review the request and
- will provide a written second opinion for the referring doctor, or
- offer a virtual or face to face consultation if The Royal Marsden can offer a different or specialist treatment, or entry into a clinical trial.
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This is the private medicine side of the RM, but might be of some use because I think it'd give you more flexibility to book with the person of your choice and more quickly:
https://www.royalmarsden.nhs.uk/private-care/second-opinion
Here's their form:
https://www.royalmarsden.nhs.uk/private-care/second-opinion/form