'almost certainly', why?
I suppose the quick answer could be that it is just the thing a Cirencester educated wannabee county set type, who go for land agent type jobs, would spend part of his budget on.
That might seem a bit flippant, but having 45 years organising horse events at a major county show, has bought me into close contact with many characters that should have gone out of circulation, when PG Wodehouse dreamed up Bertie Wooster.
Some years ago I recall seeing part of a list of corporate members of the CLA, wish I had paid more attention to it. Sadly I do not have the training of an investigative journalist, so I neither copied it or filed it, it sticks in my mind because the Powys County Council was on it and I was more interested in some issues there at the time.
Also during my time of having access to the CLA's monthly I recall reading of their ambition to have the total area of the English countryside within the membership, NT claims to be the largest landowner in the country, so their acreage of land would be well in the sights of the subscription lists.
Also I have known a few of the reps that travel the farms trying to increase the CLA's membership, an activity they have increased to a level of almost desperation since the weeding out of hereditary peers in the House of Lords.
And the chances of a volunteer knowing the financial position of all NT properties...
Just before Christmas last Mrs BWW was cornered by an NT volunteer touting for membership, she was the wife of a landowner and was out to impress, perhaps she let slip more than she should have, perhaps her blood pressure got a bit high as I had no intention of letting her passage to Mrs BWW's bank account be easy.
Mrs Landowner hyphen NT volunteer would seem to think that being close up and personal to the artifacts of past aristocracy reflected well on her own image and that many others should share that proximity, rather than truly get to know the countryside, which these historical characters have put out of bounds for future generations.