The TV series Friends undermined family values; Sesame Street taught ethnic minorities about civil disobedience; Happy Days had a subtle anti-Vietnam subtext; and the 1980s cop show MacGyver tried to persuade pistol-packing Americans that guns are bad. That, at least, is the considered opinion of Ben Shapiro, an investigative author and right-wing columnist who will publish a detailed exposé tomorrow telling how Hollywood producers, writers and actors have been secretly using TV to promote what he calls a "radical" left-leaning political agenda.

Shapiro's book, Primetime Propaganda runs to 416 pages and revolves around comments by 70-odd industry heavyweights who he approached for interviews. The book promises to "profile the biggest names in showbusiness over the past 50 years" and includes a series of "gotcha" moments, in which the architects of the best-watched TV shows of modern times tell how they tried to use the medium of broadcasting to, as Shapiro puts it, "shape America in their own leftist image".

"I was shocked by the openness of the Hollywood crowd when it came to admitting anti-conservative discrimination inside the industry," Shapiro told The Independent on Sunday. "They weren't ashamed of it. In fact, some were actually proud of it."

The book's contents will only add weight to allegations – often aired by conservative Americans – that Hollywood is the exclusive domain of leftie propagandists. Earlier this year, Republicans called for funding cuts to the public broadcaster NPR after one of its executives was secretly taped calling supporters of the Tea Party "racist".

Among Shapiro's most revelatory interviewees is Marta Kauffman, the co-creator of Friends, who recalls how she hired a "bunch of liberals" to run the programme to "put out there what we believe". In 1999, she admitted casting the actress sister of Newt Gingrich, the prominent Republican, to play a preacher at a lesbian wedding because she wanted to annoy conservatives.

"When we did the lesbian wedding, we knew there was going to be some flack," said Kauffman. "I have to say, when we cast Candice Gingrich as the minister of that wedding, there was a bit of a 'fuck you' in it to the right-wing, directly."

Elsewhere in the book, Vin DiBona, the producer of MacGyver, agrees that Hollywood has a liberal bias, saying "I'm happy about it, actually." The cult cop show advanced an anti-gun agenda, he added. "That was the whole premise of the programme, that MacGuyver used his brain power and skill and science, and solved all the difficulties through ingenuity. No Guns, no knives."

Far from being just a comedy about military camaraderie, MASH meanwhile had a pacifist agenda, the show's co-creator and director Gene Reynolds told Shapiro, who said: "We wanted to point out the wastefulness of war."

And, with regard to Happy Days, writer Bill Bickley said he "had a whole subtext" attacking the Vietnam War. "If you really look for it, you can find it."

Shapiro is relatively well known among the conservative commentariat, but believes he was able to persuade so many interviewees to reveal more than was perhaps sensible because they assumed he was a fellow liberal.

"There was a certain amount of stereotyping on their part in granting the interview," he said. "Many probably assumed that with a name like Shapiro and a Harvard Law credential, there was no need to Google me: I would have to be a leftist. In Hollywood, talking to a Jew with a Harvard Law baseball cap is like talking to someone wearing an Obama pin."

The book, published by Rupert Murdoch's HarperCollins is perhaps at its most condemnatory whenaccusing the creators of Sesame Street of attempting to brainwash young children. It quotes Mike Dann, one of the show's founding executives, saying it "was not made for the sophisticated or the middle class".

Early episodes featured the character Grover breaking bread with a hippie. Oscar, who lived in a rubbish bin, was supposed to address "conflicts arising from racial and ethnic diversity".

"Sesame Street tried to tackle divorce, tackled 'peaceful conflict resolution' in the aftermath of 9/11 and had [gay actor] Neil Patrick Harris on the show playing the subtly-named 'fairy shoeperson'," notes Shapiro.