How to get the IVC/SRN for UK stock holdings?

IBKR does not provide the Investor Code (IVC) or Shareholder Reference Number (SRN) for UK equities to customer.

Powered by IBot
What is the KELER code for TBSZ Transfers?
Where can I find my SRN number?
How to get the SRN for Australian stock holdings?
What is an SRN?