trouble with medium wave is that you require a decent sized antenna and ground system and somewhere to have it all setup in.

In todays world of camera phones, surveillance, nanny-state policing plus not to mention thieves and crooks everywhere... the e-bike phone thieves, fancy watch thieves, push-bike thieves,
you'd have to contend with transmitter thieves and playback system thieves...

There isn't the vacant land and scrub lands around like there used to be and besides there's just too many people everywhere..

Then there's the noise floor issue.. 10 watts isn't going to crack it.. you'd need probably at least 80 watts and a good radiating antenna... after which you might be lucky to get half a dozen listeners..

I think there should be a new pirate band for the UK that is for enthusiasts (anoraks) that's can be operated mobile/portable..

Perhaps somewhere around the 150 - 170 mHz band using 25 kHz 16KOF3E channel bandwidth FM. Or even in the 30 - 70 mHz part of the spectrum.