BBC Two - Gardeners' World, 2018, Episode 15
It is called 'the Secret Valley':
The Secret Valley | A tranquil escape within the suburbs of Manchester | Thesecretvalley.com
And has really caught the public eye:
Old grimy coal yard has transformed into a magical secret garden | UK | News | Express.co.uk
This looks like an ordinary house - but it has a very special secret garden - Manchester Evening News
The Secret Valley
Large 2 acre water garden with ponds, streams, waterfalls, islands and lake.
High variety of trees, plants and climbers.
It is a haven for waterfowl and local wildlife (incl swans, ducks, geese, coots, moorhens, grebes, herons and kingfishers).
Adjoining gardens and allotment are also open.