Possible Clues:

• Half-hearted step I'd taken
• Like old bathwater
• Unenthusiastic little boy, about three and a bit
• Lukewarm's food returned around start of 'Porridge'
• Unenthusiastic leader of party in parliament shown up
• Decidedly unenthusiastic
• Not exactly enthusiastic
• Unenthusiastic, as a reaction
• Hardly enthusiastic, as a reaction
• Having an underwhelmed response