Don't the embassies primarily support British businesses abroad? I think the answer is in business relationships.

While the government can ignore many voters business is more sensitive to public image. Their Thailand association is affiliated to the government body that is appeasing hazard to expats.

I think the government would take tax from Tesco Lotus and many others over putting pressure on safety for individual tourists abroad.

Not sure how long this will remain accesible in Thailand, but Anonymous (claimed) have posted a lengthy video on recent murders/deaths in Thailand culminating in an appeal for a Thailand boycott. Kristy Jones is mentioned in from 6 min 10 secs.