Possible Clues:

• Heartless workers' group set up -- not liked by the toffs
• Less than posh
• Socially unacceptable foreign noun
• Lower class
• Common name, reflecting one from Madrid
• Common
• Uncultured
• Return of workers' organisation one dismissed as unacceptable to toffs
• Unacceptable, socially
• Lower class group of workers losing heart in revolution