Update; A much better version of this map, plus others, is available at the 1:2500 maps page.
OS maps are covered by Crown Copyright which expires 50 years after publication. The actual date for this map isn’t clear – it’s the 1901 edition re-levelled in 1923, but may have been printed later. However, It does seem certain it was printed before 1960, which makes it out of copyright. So, this image is placed in the public domain.