Might we thus describe Amundsen’s arrival at 12 for a 19? (8)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

The Norwegian explorer Roald Amundsen arrived at the South Pole (12a) a few weeks before Scott’s British expedition – so PRE-SCOTT. Reference to 19a BARON: the Labour politician John Prescott, now Baron Prescott.