I am a teacher in a primary school in South Africa and our learners are using the Kathy and Mark series published by James Nisbet & Co as a basic class reader.  This series is quite westernised and colonial and a team of educators would like to adapt the series to make it more suitable for our South African context.  Do I need a publisher's (or author's) permission?  I am experiencing some difficulty locating contact details for James Nisbet & Co.  Does anybody have any advice, information or suggestions?