According to various interviews and behind-the-scenes accounts, filming the bedroom scene with Rosie Taylor-Ritson (Celia Gray) and the other child actors was a carefully managed and supportive process.

Comfort and Safety: 1. Director Susanna White ensured the child actors felt comfortable and safe during filming.

2. Rosie Taylor-Ritson reportedly felt at ease wearing the iconic slip, which was designed to be comfortable and suitable for her age. 3.

The film's costume department took care to ensure the slip was not too revealing or uncomfortable for Rosie.

On-Set Atmosphere: 1.

The child actors, including Rosie, were encouraged to have fun and play together during filming breaks. 2.

The bedroom scene was filmed in a relaxed atmosphere, with the director and crew prioritizing the children's comfort.

3. Rosie has mentioned in interviews that she enjoyed working with the other child actors and felt like they were all "mates." Rosie's Perspective:

In an interview with BBC Radio 4's "Front Row" (2010), Rosie Taylor-Ritson discussed filming the bedroom scene: "It was really fun... We all got on really well... The slip was really comfy, actually... It was like wearing a nightie."

Sources: 1. BBC Radio 4's "Front Row" (2010)

2. The Guardian's "Nanny McPhee and the Big Bang" interview (2010)

3. Behind-the-scenes featurettes on the DVD/Blu-ray release Keep in mind that these sources might not provide exhaustive information, but they offer insight into the filming process and Rosie's experience.