Dr Thompson's Underground Clinic is a clinic in London, where illegal abortions are carried out. It is located in a flat in a London townhouse.
Series Four Edit
When Lady Edith falls pregnant after a night (or rather morning) of passion with her lover, the missing Michael Gregson, she decides that the baby must be aborted. After finding an advertisement in The Lady for Doctor Thompson's clinic, she goes there with Lady Rosamund. However, she suffers a change of heart when she gets there, saying that it had 'been a mistake'.