I have seen reports that a new channel is testing on Freeview via PSB3 - ONLY for viewers who can pick up:
*BBC 1 HD
*BBC 2 HD
*ITV1/STV/UTV HD
*BBC Scotland HD (Scotland only)
*S4C HD (Wales only)
*Channel 5 HD
*BBC 3 HD
*BBC 4 HD
*Channel 4 HD
*CBBC HD
*CBeebies HD
*TBN UK
*5SELECT
https://feddit.uk/post/18635722