“Frankly, I could carve a better opposition party out of a banana than the Tories.”

Speech to the Labour Party Conference (3 October 1988), quoted in "Scargill in furious attack on reform", The Times (4 October 1988), p. 9

Source: Unseen Academicals

Source: Speech at banquet of the National Union of Conservative and Constitutional Associations, Crystal Palace, London (24 June 1872), cited in "Mr. Disraeli at Sydenham," The Times (25 June 1872), p. 7.

As quoted in Abstract Art, Anna Moszynska, Thames and Hudson 1990, p. 206
quote after 1959, in Andre's early artistic career, when he made his sculpture 'Last Ladder'

There is no evidence that Skinner said this. But see quotation from 1 April 1981, above.
It is an old joke which has been around since at least 1927 http://quoteinvestigator.com/2014/04/19/half-fools/.
Misattributed
Variant: Skinner: "Half the Tories opposite are crooks."
Source: "Dennis Skinner Did Not Call Half the Tories Crooks (and How to Verify Other Quotes from Parliament)" https://clioseyeroll.wordpress.com/2016/12/03/dennis-skinner-did-not-call-half-the-tories-crooks-and-how-to-verify-other-quotes-from-parliament/, 03 December 2016.

"My Beef With Ann Coulter" in The Daily Beast (9 March 2009) http://www.thedailybeast.com/blogs-and-stories/2009-03-09/my-beef-with-ann-coulter/
Context: Certain individuals continue to perpetuate negative stereotypes about Republicans. Especially Republican women. Who do I feel is the biggest culprit? Ann Coulter. I straight up don’t understand this woman or her popularity. I find her offensive, radical, insulting, and confusing all at the same time. But no matter how much you or I disagree with her, the cult that follows Coulter cannot be denied. She is a New York Times best-selling author and one of the most notable female members of the Republican Party. She was one of the headliners at the recent CPAC conference (but when your competition is a teenager who has a dream about the Republican Party and Stephen Baldwin, it’s not really saying that much).
Coulter could be the poster woman for the most extreme side of the Republican Party. And in some ways I could be the poster woman for the opposite. I consider myself a progressive Republican, but here is what I don’t get about Coulter: Is she for real or not? Are some of her statements just gimmicks to gain publicity for her books or does she actually believe the things she says? Does she really believe all Jewish people should be “perfected” and become Christians? And what was she thinking when she said Hillary Clinton was more conservative than my father during the last election? If you truly have the GOP’s best interests at heart, how can you possibly justify telling an audience of millions that a Democrat would be a better leader than the Republican presidential candidate? (I asked Ann for comment on this column, including many of the above questions, but she did not answer my request.)

Maiden speech on 24 May 2005

"No one obeys the speed limit except a motorised rickshaw", Daily Telegraph, 12 July 2001, p. 27.
2000s, 2001

As quoted in "Angus King joins race for Senate" by Jonathan Riskind in The Kennebec Journal (6 March 2012) http://www.kjonline.com/news/angus-king-joins-race-for-senate_2012-03-05.html