Thanks for this. The original letter referred to "the structure being built on the flat roof" After I had spoken to them and mentioned that it had been there circa 20 years, sent pictures of the deck from when I had purchased the property 12 years ago together with the sales details mentioning the deck, they replied with the following letter:
"Thank you for your emails and phone calls regarding the above property. I sincerely apologise for the delay in contacting you.
Having had a discussion with the Planning Services Manager, I can confirm that the roof terrace erected does not benefit from the 4 year 'deemed consent' rule because the structure has been significantly replaced. I therefore ask that the roof terrace is removed within 3 weeks of the date of this letter.
As stated in previous correspondence, we are not inviting a planning application for this structure as we deem it unlikely consent would be given in its current form. However, you are still entitled to submit a planning application which would be assessed without prejudice. If this application was then refused, you would have a right of appeal to the Planning Inspectorate."
The neighbour, removed their deck a couple of years ago as it was too costly to repair and they were intending to rent out the property. I contacted them and they are in full support of my deck and had intended to reinstate their deck when they moved back to live in the house. I don't know who complained, but it is likely to be the tenant in the house next door.
I spoke to the enforcement officer and she said I could not appeal until they issued the enforcement notice. She has been on holiday since...