A time-traveller from another culture - say that of ancient Greece - would be puzzled by this line of thought. Surely, they would argue, if the Opposition was not being political, then it had no business in the House? Supposing a mathematician were to produce an elegant new formula that his colleagues had overlooked. Would they get level with him by accusing him of being too mathematical? But then the ancient Greeks held politics in as high regard as we do maths. Indeed they invented the word, polis being the state and its citizens, a politikos a statesman; as an adjective it sometimes meant "statesmanlike". Aristotle was not being rude when he said man was a political animal. In his scheme of things a government which governed in its own interests, rather than in those of its citizens, was a "deviation". Today the very word political, exchanged across the floor, means devious.
All very sad, but alas not exactly new. Johnson told Boswell in 1775 that "modern politics were entirely devoid of all principle of whatever kind", and that they were "now nothing more than a means of rising in the world", though a politico had already been a term of contempt for 100 years. Johnson thought the rot had set in after King Charles II's day. But Shakespeare's Lear had been talking about scurvy politicians even in the time of good King James I.