A Tory MP caught colleagues in parliament off guard on Monday evening by expressing surprise at the popularity of S&M.
During a Commons debate on the environment, former cabinet minister Peter Lilley said he was "puzzled" at why the green lobby was committed to "perverse policies".
"I found a possible hint of an explanation, when someone mentioned to me, Madam Deputy Speaker, a book that I am sure that, like me, you have not read but have heard about called 'Forty Shades of Grey'. It is apparently a mildly pornographic," he said.
Tory Graham Stuart pointed out the book was called 'Fifty Shades of Grey' not 'Forty'.
One guffawing MP shouted across at Stuart that "he would know". And another yelled out that perhaps the downgrading of the book from fifty to forty was a result of "Tory cuts".
Jamie Dornan and Dakota Johnson in the film version of 'Fifty Shades of Grey'
Lilley, 72, insisted he did not know the name of the book because he had not gone anywhere near it. "Have I any higher bids? I have not read it; I have not even read the title of it," he claimed.
"However, the surprising popularity of that book demonstrated that sadomasochism, or the infliction of pain and the submission to pain, are far more widespread tastes than we had previously thought.
"It seems to me that in the political sphere there is a similar belief that it would be popular to inflict pain or submit to pain by green policies. We might say that what we are suffering from in this country is 'Fifty shades of green'.
"The trouble is that Members who are committed to this doctrine measure the success of their policies not by what they will achieve, but by what they will cost, and not by how effectively they will reach a given destination, but by how onerous are the burdens they can place on Britain, British households and British business.
Lilley added: "That pain is very significant."
Ed Miliband had the job of following Lilley's unexpected analogy. "It is a privilege to follow the unique speech of the right hon. Member for Hitchin and Harpenden (Lilley)," the former Labour leader told Commons. "I bow to his greater knowledge about 40 or 50 shades of grey—or green, for that matter."