The 50yr anniversary of Gardeners’ World, was celebrated by the RHS magazine, The Garden, in the April 2017 edition: https://www.rhs.org.uk/about-the-rhs/publications/magazines/the-garden/2017-issues/April/a-world-of-gardening-in-50-years.pdf
Gardeners’ World was a BBC Birmingham production until it was moved to BBC Bristol in 2012.
The article gives a timeline of the presenters of the UK’s favourite gardening show:
1968-76 – Percy Thrower
1976-79 – Arthur Billit
1979-96 – Geoff Hamilton
1980-2 – Geoffrey Smith
1996-2002 – Alan Titchmarsh
2003-8 – Monty Don
2008-10 – Toby Buckland
2011-present – Monty Don