Saturday's Nordoff-Robbins benefit concert at England's Knebworth Park (30 miles outside London) will probably be the rock event of the summer, bringing together such mega-stars as Paul McCartney, Eric Clapton, Phil Collins (with and without Genesis), Mark Knopfler, Elton John, Tears for Fears and Pink Floyd (George Michael was supposed to be on the program but dropped out because of "recording pressures"). While the show's being broadcast live in more than 60 countries, there will be a two-week wait before "Rock It" makes it to American television via MTV (as a five-hour highlight special July 14). MTV will provide live coverage of the concert from noon to 6 p.m. on Saturday, mostly backstage interviews. However, the entire concert can be heard live on the Westwood One radio network.

Producers hope to raise $10 million for the Nordoff-Robbins Foundation, a medical organization that uses music therapy to reach handicapped children and that has become a favorite charity for British pop stars (it benefited from the Who's "Tommy" performances last year). The Nordoff-Robbins Music Therapy Center has been operating in England since 1959, and in 1976 started awarding a Silver Clef to British artists for career achievement, with the annual awards luncheon serving as a fund-raiser (most of the performers at Saturday's concert are past winners). An American Silver Clef award was initiated in 1988 and a stateside Nordoff-Robbins Center will open in New York later this year. Unlike some other mega-shows, this one will be followed by a live album and a video, both available in the fall.

Mac Attacks

Paul McCartney, of course, is coming to town for RFK Stadium concerts next Wednesday and Friday. While the Independence Day concert is technically sold out, some 200 prime floor seats are still available -- and you don't need a Visa Gold Card to get them. All you have to do is is contribute at least $100 to Friends of the Earth, the global environmental advocacy group. Last year McCartney, a vegetarian and longtime environmentalist, invited FOE to use his world tour as a platform to focus public attention on environmental perils around the world (FOE has chapters in 38 countries). Some 200 FOE tickets are available for Friday's show as well; contributors will also receive a year's membership in FOE and a monthly news magazine. Contributions are tax deductible after the first $50, and current FOE members can finagle a ticket with an additional contribution of $100. To arrange membership and pickup of the tickets, call (202) 544-0309.

Next Wednesday afternoon, Paul and Linda McCartney will be at RFK Stadium taping a message for People for the Ethical Treatment of Animals' National Action Hotline (their message will run for a week or so). PETA has also been invited to set up information tables on this leg of the tour. The McCartneys also posed for the cover of PETA's 1990 Christmas catalogue, which will be out in the fall. It promotes T-shirts, vegetarian cookbooks and various "cruelty-free" products. Also featured as models: Elvira, Belinda Carlisle and k.d. lang.

Wall Up

Pink Floyd's "The Wall" is one of the biggest-selling albums of all time, and it may become one of the biggest rock concerts as well when it's performed live on July 21 in Berlin's Potzdamer Platz, the no man's land between East and West Berlin. However, it won't be a Pink Floyd show, but a Roger Waters extravaganza. Waters was the Floyd's leader and conceptualist before leaving the group in 1986. There were subsequent legal battles over the group's name, props and Gerald Scarfe-designed stage sets, and even the reunification of the two Germanys seemed more likely than a full Floyd get-together.

The July concert will be organized on a massive scale: 300 extras, the Berlin Symphony Orchestra and Red Army Choir, major musical guests (including Sinead O'Connor as the female lead), planes, helicopters and troops from both the East and West German armies (apparently desperate for work these days). The Floyds were always known for their huge inflatable props, and the "Teacher" to be used here is 80 feet high, with a 45-foot-wide head and 60-foot-long arms. A live album will be out on PolyGram in the fall, followed by a concert video; negotiations are underway now for it to be carried live on television.

"The Wall," which sold 19 million copies worldwide and spent 15 weeks at the top of the American charts, has only been performed in four sites, and this will be the first outdoor version. In the original 1981 production, a 40-foot-high by 160-foot-wide wall was constructed across the stage as the band performed, gradually blocking it off from the audience (to reinforce the theme of alienation). At the end the wall came tumbling down. The new wall will measure 60 feet by 600 feet. Ironically, Waters decided that the show needed a new ending in light of developments in Eastern Europe, so the new finale will be "The Tide Is Turning" from his first solo album.

The 1982 film version of "The Wall" starred little-known Irish rock singer Bob Geldof, who later became better known as the originator of Band Aid and Live Aid, which raised more than $150 million and kicked off the whole rock charity movement. Proceeds from the "Wall" concert, which could attract 250,000 people, will go to the British-based charity the Memorial Fund for Disaster Relief.