Thanks for all the replies.

Responding to a number of suggestions relating to using the adjacent building to brace the ladder- unfortunately,that is not an option in this case. There is a space of about 8 feet between the buildings, but with a fence dividing that space. The reality is that the maximum distance from my house that I can rest the ladder base is about 3 feet.

I watched the Dibnah vid on laddering a chimney some time back. Amazing chap. Can't recall whether it's that vid, or a different one, where he climbs an old tower with a big ledge at the top and with his ladders strapped around the downward-facing underside of the ledge. It looked terrifying.

I'm no Dibnah and the height of working will be up to gutter level of a two storey house. I have a small platform to get a lower bracket fixed to the wall at, say, 8 to 10 feet up. With that in place, I could fix the ladder and get another bracket higher up. My plan was to use a harness because I appreciate that hanging on without gravity in my favour would be tricky!

Thanks.

Bill.