I don't know if anyone has seen or mentioned this, but whilst searching online i found a Watson W-8686 on https://www.nevadaradio.co.uk/product/watson-w-8686/ seems like the station thats been mentioned in this thread. Price is £189.95, i downloaded the info sheet and says the outdoor sensor will operate on 433 or 868Mhz depending on location.
Been looking at replacing my ws1001 (maplin clone) so may order this in the next few weeks.