The air show debut of the 737 MAX and major agreements for the U.K. to acquire P-8 and Apache aircraft marked a busy first day at the Farnborough International Airshow outside London.

British Prime Minister David Cameron and Boeing Chairman, President and CEO Dennis Muilenburg met at the show to highlight an initiative announced Monday that sees Boeing jointly invest in, develop and operate a base for nine P-8 multi-mission aircraft for the U.K. Royal Air Force.

“We’re very excited about this,” Cameron told Muilenburg as they stood in front of the P-8, which will fly in the air display this week.

The U.K. Ministry of Defence also announced it will upgrade its attack helicopter fleet with 50 Boeing AH-64E Apaches.

“This deal will give the British Army an outstanding helicopter,” said British Defence Secretary Michael Fallon, explaining that the P-8s and Apaches formed part of a plan for “stronger and better defense.”

Much of the air display portion was rained out, but that didn’t dampen business for the 737 MAX. Customers reaffirmed the airplane’s position at the heart of the single-aisle market, the biggest sector in commercial aviation.

China’s Xiamen Airlines signed a Memorandum of Understanding for up to 30 737 MAX 200 for its low-cost-carrier operating units. Donghai Airlines signed an Intent to Purchase for 25 737 MAX 8s along with five 787-9s.

Later, the 737 MAX was at the core of Boeing’s biggest ever services contract announcement. Norwegian committed to expanding GoldCare coverage from its existing 787 fleet to its entire fleet of 108 737 MAXs on order.

“Boeing has proven to us over the past four years the value of GoldCare for our operations,” said Bjorn Kjos, Norwegian CEO. “The reliability and operational effectiveness of our 787 fleet has never been better. We have great expectations and confidence in what we can accomplish by leveraging GoldCare across our 737 MAX fleet as well.”

Boeing also reaffirmed the 737 MAX’s importance in its annual 20-year forecast for the commercial airline market, in which it projected demand for 39,620 new airplanes, a 4.1-percent increase over last year’s forecast, with an estimated value of $5.9 trillion.

The single-aisle market will be especially strong, with low-cost carriers and emerging markets driving growth. 28,140 new airplanes will be needed in this segment, more than a 5-percent increase over last year.

“There’s no question the heart of the single-aisle market is around the new Boeing 737 MAX 8 and the current 737-800,” said Randy Tinseth, Boeing Commercial Airplanes vice president of Marketing. “Airplanes that size already account for 76 percent of the global single-aisle backlog, and our products have the clear advantage in that space.”

With Boeing celebrating its 100th year on July 15, the Centennial Experience pavilion at the show drew crowds to experience an innovative interactive exhibit to showcase the company’s legacy and its future.

Also on show at Farnborough is an ANA 787-9 Dreamliner performing a dazzling routine that is available to view in its rehearsal flight here as well as the Boeing F/A-18 and P-8 military aircraft and a 747-8 freighter, operated by Cargologic, on static display.