What does "Doesn't half go on" mean? The full context:
"..said Dad impatiently. 'You don't go to Llanpistyll to go shopping.' 'Obviously not,' said Mum. She sighed. 'I like shopping.' 'So do I,' I said. Dad sighed too. Even more impatiently. 'Boys don't like shopping,' he said. 'I worry about you sometimes, Tim.' I worry about my dad sometimes too. He doesn't half go on. And on and on. "
(From "Buried Alive", a children book)