Possible Clues:

• Spanish gentleman
• Foreign gentleman in conspiracy takes devious role
• *Southwestern horseman
• Gentleman's vehicle has everything — nothing fails to start
• Spanish gentleman's unusual role supporting secret plot
• Spanish gentleman's role loosely associated with plot
• Rider means group of plotters has new role
• Spanish gentleman hired vehicle to go across the Pyrenees, coming to nothing
• Spanish gent about to join dance - 'erculean fellow
• Foreign gent rented vehicle in France to go round