For the last few days both Challenge Tv and Pick TV have been available free to air / FTA.

This mean that they do not require a sky card to view.

Challenge TV is / was part of the Sky subscription service.
Pick TV is / was “free to view” and although did not require a subscription, did requrie a viewing card.

Challenge TV is available on Sky channel 125
Pick TV is available on Sky channel 152

Frequencies:
If you do not have a SKy box then these are the frequencies for these two channels:

Challenge TV frequency 11.565 V, SR 27.500, FEC 2/3
Pick TV frequency 12.207 V, SR 27.500, FEC 2/3

It is unknown if these channels being available for free is temporary, a glitch, or permanent.