So this year we made the decision to demolish it completely and replace it with a new structure, preferably one we can sit in on a blustery or rainy day and still enjoy the sunshine, which this end of the garden enjoys all day round.
The following video shows the operation to demolish it. Pepsi and Max are popping in and out of the frame all the time and it finishes rather abruptly as we realise that Pepsi has disappeared through a gap we had exposed in the fence (it used to have chicken wire attached to the greenhouse to stop him!), which is when we had to drop everything temporarily and chase him across the field down to the river which backs on to the garden! Didn't do poor Hubby's blood pressure a lot of good either!