I sympathise with the Royal Mail workers, but suspect they are onto a loser with these strikes.
The money making part of the Royal Mail is the parcels service, which unfortunately for the workers is the one area where there is major commercial competition (which isn't on strike). Many commercial users of the royal mail pacels service will be jumping ship to these private companies after these strikes, leaving them with the loss making letters service, (with the universal coverage commitment) so job losses in the Royal Mail will be worse than ever.