Playing basic Acol at a local low key club. Partner opened 1 Club. I had 15 odd points, 5 Clubs, 3 Diamonds, 3 Hearts, 2 Spades. I considered responding 3NT but thought I'd be clever and respond 1 Diamond and await a reply. Ended in 6 Clubs making.
After the play one of the opponents politely asked about my 1 Diamond response with only three cards in the suit.
Was what I did against 'the rules' in any sense ?