When was the book Indian in the Cupboard written?

The Indian in the Cupboard by British authoress Lynne Reid Banks was published in 1980, and was made into a film in 1995.

It was followed by four sequel books, The Return of the Indian in 1985, The Secret of the Indian in 1989, The Mystery of the Cupboard in 1992 and finally The Key to the Indian in 1998.

The books are About a Boy that finds out that a toy plastic Indian comes to life when he puts it in the bathroom cupboard.