Sir Simon was a well-connected individual known to Giles, the director of P.R.O.B.E., by 2023.
When Giles phoned him and explained that he needed a way to safely send H. P. Lovecraft back to his own era, Sir Simon "called in a few favours" and was able to arrange the transfer of a device that had been in storage in an "unforgotten military archive" associated with an institute in Wales, which allowed for safe travel through rifts. (AUDIO: Guardian At The Gate)