At the end of the 1970 film "The Railway Children", who holds up a slate with "The End" written in chalk?

"The Railway Children" is a 1970 British drama film based on the 1906 novel of the same name by E. Nesbit. The film was directed by Lionel Jeffries and stars Dinah Sheridan, Jenny Agutter (who had earlier featured in the successful BBC's 1968 dramatisation of the novel), Sally Thomsett and Bernard Cribbins in leading roles. The film was released to cinemas in the United Kingdom on 21 December 1970.

The entire cast perform a curtain call as the credits roll. The camera moves slowly along a railway track towards a train which is decked in flags, in front of which all of the cast are assembled, waving and cheering to the camera. At the start of the credit sequence, a voice can be heard shouting "Thank you, Mr Forbes" to acknowledge producer Bryan Forbes. At the end, Roberta 'Bobbie' Waterbury (Jenny Agutter) holds up a small slate on which "The End" is written in chalk.