Device (Guardian At The Gate)

A device resembling a large wristwatch was "cobbled together" by an institute in Wales to help "deal" with a rogue time traveller who had built a machine that created unstable rifts. It allowed the wearer to pass through such a rift without risk. After the institute were done with it, the now-useless device was stored in a military archive. Eventually, P.R.O.B.E. acquired it through Sir Simon in order to ensure that nothing would go wrong when sending H. P. Lovecraft back through the unexplained, unstable time rift which had flung him from the 1930s to 2023. To avoid any damage to history, Lovecraft was instructed to destroy the device as soon as he was safely home, and to throw its remains into the sea. (AUDIO: Guardian At The Gate)

Behind the scenes
With the "institute in Wales" implicitly being Torchwood Three, the description of the device implies it was modified from a broken vortex manipulator. However, this was not made explicit.