Filming
Principal photography began in the Canton of Bern, Switzerland, on 21 October 1968, with the first scene shot being an aerial view of Bond ascending the stairs of Blofeld's mountain clinic to meet the patients. The scenes were shot at the revolving restaurant Piz Gloria, located atop the Schilthorn near the village of Mürren. The location was found by production manager Hubert Fröhlich after three weeks of location scouting in France and Switzerland. The restaurant was still under construction, but the producers found the location visually interesting for film-making, and agreed to finance the provision of electricity and the aerial lift to make filming there possible.
The first ski chase scene in the Alps was shot on various ski runs around the Schilthorn and Wengen and the second one on the Sulegg, as well as Winterburg Hill, Heiligenschwendi. The Christmas festival was filmed in Grindelwald, and Bond's spy mission in a lawyer's office was shot in Bern. Production was hampered by weak snowfall which was unfavourable to the skiing action scenes. The producers even considered moving to another location in Switzerland, but it was taken by the production of Downhill Racer. The Swiss filming ended up running 56 days over schedule. In March 1969, production moved to England, with London's Pinewood Studios being used for interior scenes, including those set at Piz Gloria, and M's house being shot in Marlow, Buckinghamshire. In April, the filmmakers went to Portugal, where principal photography wrapped in May.
The pre-credit coastal and hotel scenes were filmed at Hotel Estoril Palacio in Estoril and Guincho Beach, Cascais, while Lisbon was used for the reunion of Bond and Tracy, and the ending employed a mountain road in the Arrábida National Park near Setúbal. Harry Saltzman wanted these scenes to be in France, but after searching there, Peter Hunt considered that not only were the locations not photogenic, but were already "overexposed".
While the first unit shot at Piz Gloria, the second unit, led by John Glen, started filming the ski chases. The downhill skiing involved professional skiers, and various camera tricks. Some cameras were handheld, with the operators holding them as they were going downhill with the stuntmen, and others were aerial, with cameramen Johnny Jordan – who had previously worked in the helicopter battle of You Only Live Twice — developing a system where he was dangled by an 18 feet (5.5 m) long parachute harness rig below a helicopter, allowing scenes to be shot on the move from any angle. The bobsledding chase was also filmed with the help of Swiss Olympic athletes, and was rewritten to incorporate the accidents the stuntmen suffered during shooting, such as the scene where Bond falls from the sled. Blofeld getting snared with a tree was performed at the studio by Savalas himself, after the attempt to do this by the stuntman on location came out wrong. Heinz Lau and Robert Zimmermann served as the stunt doubles for Bond and Blofeld during the bobsleigh scene. Glen was also the editor of the film, employing a style similar to the one used by Hunt in the previous Bond films, with fast motion in the action scenes and exaggerated sound effects.The avalanche scenes were due to be filmed in co-operation with the Swiss army, which annually used explosions to prevent snow build-up by causing avalanches, but the area chosen naturally avalanched just before filming. The final result was a combination of a man-made avalanche at an isolated Swiss location shot by the second unit, stock footage, and images created by the special effects crew with salt. The stuntmen were filmed later, added by optical effects. For the scene in which Bond and Tracy crash into a stock car race while being pursued, an ice rink was constructed over an unused aeroplane track, with water and snow sprayed on it constantly. Lazenby and Rigg did most of the driving due to the high number of close-ups.
For the cinematography, Hunt aimed for a "simple, but glamorous style like the 1950s Hollywood films I grew up with", as well as something realistic, "where the sets don't look like sets". Cinematographer Michael Reed added he had difficulties with lighting, as every set built for the film had a ceiling, preventing spotlights from being hung from above. While shooting, Hunt wanted "the most interesting framings possible", which would also look good after being cropped for television.
Lazenby said he experienced difficulties during shooting, not receiving any coaching despite his lack of acting experience, and with director Hunt never addressing him directly, only through his assistant. Lazenby claimed that Hunt also asked the rest of the crew to keep a distance from him, as "Peter thought the more I was alone, the better I would be as James Bond." Allegedly, there also were personality conflicts with Rigg, who was already an established star. However, according to Hunt, these rumours are untrue and there were no such difficulties—or else they were minor—and may have started with Rigg joking to Lazenby before filming a love scene, "Hey George, I'm having garlic for lunch. I hope you are!"
Hunt also declared that he usually had long talks with Lazenby before and during shooting. For instance, to shoot Tracy's death scene, Hunt brought Lazenby to the set at 8 o'clock in the morning and made him rehearse all day long, "and I broke him down until he was absolutely exhausted, and by the time we shot it at five o'clock, he was exhausted, and that's how I got the performance." Hunt said that if Lazenby had remained in the role, he would also have directed the successor film, Diamonds Are Forever, and that his original intention had been to conclude the film with Bond and Tracy driving off following their wedding, saving Tracy's murder for the pre-credit sequence of Diamonds Are Forever. The idea was discarded after Lazenby quit the role.
On Her Majesty's Secret Service was the longest Bond film until Casino Royale was released in 2006. Even so, two scenes were deleted from the final print: Irma Bunt spying on Bond as he buys a wedding ring for Tracy, and a chase over London rooftops and into the Royal Mail underground rail system after Bond's conversation with Sir Hilary Bray was overheard.