Thank you for your reply, and for proving that I am not being paranoid!
To clarify further, the donation forms I fill in and send with the money state "Thank you for voluntarily donating funds to the XXX. Please note that there is no formal contractual relationship between the XXX and Garden Owners."
If I understand you correctly, this sentence deliberately quashes any implied agreement so the full gross takings would should be declared as personal income and subject to income tax.
This means so far I have been engineered into not declaring £17,000, so going forward my goal is to retain 40% of the takings for the tax bill, to declare the takings as personal income and pay the tax accordingly from the retained takings, and send only the remainder to the XXX, however I would need a professional accountants letter clarifying my current position and advising me to do this before I approach the XXX to tell them this is my plan. I suspect from their small print they are fully aware of having engineered me into this position, so I need to be able to present my position clearly, calmly and as a foregone conclusion. Is this something you are certified to do for me? If so, please let me know your fee for agreeing the text and posting the letter.
A nebulous body that should not be tolerated under any circumstances - you've met my father!
Seriously, I am trying to be level headed about this. Once I realised the outrage, then ran though the implications for all the other garden owners, the finances and structure of said nebulous body and my own position in relation to it, I am trying to work out a secure position with no presumption of trust on the part of the other party. From past experience (see above!) I know there's nothing like documented facts in my back pocket when engaging with nebulous bodies. I am happy to pay a moderate amount to arm myself with said letter, just to fortify myself against the fog before I engage- just getting my ducks in a row.
Gut reaction is to stop dealing with the XXX, but I don't want to throw the baby out with the bathwater and stop doing the open garden days, as it has generated garden design work and press coverage for the gardens, and I hope to build a regular visitor base through the XXX open days so I can dispense with the nebulous body at a time of my choosing.
I hope this answers your question "why?" - would you be willing to write my fortifying letter?
Sorry - I hope my conundrum didn't raise your blood pressure! You have been extremely helpful and I am very grateful for your advice, but I will let you off the hook and do it through a local tax accountancy firm, now I know I'm not imagining things!
Enjoy your holiday,