 | Tom Courtenay als Grandpa |
 | Kit Connor als Jack |
 | Jennifer Saunders als Miss Dandy |
 | David Walliams als Barry |
 | Samantha Spiro als Patricia |
 | Alice Nokes als Shelley |
 | Frankie Fox als Dazza |
 | Michele Dotrice als Miss Trifle |
 | Katy Brand als Miss Verity |
 | Harish Patel als Raj |
 | Ralph Riach als Mr. Willkins |
 | Rafe Spall als Adult Jack (voice) |
| Elliot Hegarty | Director |
| Richard Mott | Director of Photography |
| Julie Dorrat-Keenan | Makeup Supervisor |
| Gwilym Perry | Foley Editor |
| Andy Merchant | Stunts |
| Alan Maxwell | Camera Operator |
| Chris Pollard | Stunts |
| Chris Lyons | Makeup Effects |
| Jacqui Mallett | Makeup Department Head |
| Karie-Ann Robinson | Chaperone |
| Iain McDonald | Production Design |
| Jacqui Mallett | Makeup Designer |
| Cathy Prior | Costume Supervisor |
| Suzanne Field | Art Direction |
| Lucy Enfield | Script Supervisor |
| Matt Biffa | Music Supervisor |
| Francesca Falchi-Pereira | Production Coordinator |
| Peter Oliver | Editor |
| Tim Zaccheo | Visual Effects Supervisor |
| Dave Thom | Gaffer |
| Conor Mackenzie | Lighting Technician |
| Martin Newstead | Steadicam Operator |
| Amy Swan | Assistant Editor |
| Kevin Cecil | Adaptation |
| David Walliams | Writer |
