Well, after studying my 6m out, 2.5m high plank of wood he's been round to say he will object. I've told him we'll apply anyway, (up to the boundary with a taller eaves and roof height than offered - in case that gives us a bit of wiggle room with the council) but if it gets rejected we'll be extending out 3m to the absolute limits of PD together with a 7m x 2.5m x 2.5m high (plus the extra because the ground slopes up) garden room along the boundary. Far from ideal but as the extra space is primarily for our two teenagers and friends it will do for us if it has to. In my NCS description I will (for my neighbours benefit and extremely politely) include full details of the alternative proposal, making it clear that it's all PD with no right to object. I will state my willingness to work with all parties to achieve something acceptable. The council will see this and hopefully agree that Plan A isn't the worst that could happen, or knowing my luck interpret it as a veiled threat and start sharpening their claws! Sadly whatever happens our neighbours and us are now definitely off each others Christmas lists!