From David Kenney's account of the recapture of South Georgia

Galtieri's seizure of the Falklands could not have been worse timed for Margaret Thatcher. Race riots in English cities, high unemployment and back bench grumbling had eroded her dominance over the Conservative Party and the House of Commons. After the Falkands fell she fired her Foreign Secretary, useful and necessary under the circumstances, but had to accept as a replacement Francis Pym(1) whose hawkishness towards the Argentineans remained in doubt until war's end. Thatcher and Pym shared a mutual dislike and mistrust. Her Foreign Office had commited that gravest of burocratic blunders, it had gestated a minor perplexity into a major crisis. She could not repose confidence in her intelligence community after its failure to assess accurately Argentina's overt preparations for war.