In the meantime my land lady's sister who lives in my village generously offered me her shower if I needed one. Eventually, after washing in cold water for a few days, I took her up on her offer and enjoyed a rather luxurious shower at her house. It reminded me of how nice a hot shower was and I looked forward to the guy coming round to sort mine out. It took him nearly a day. The pipe in the picture below is my old flue. Note there is no covering on the outside.
The pictures below are the old boiler and the brand new one and the old boiler in the garden waiting to be taken away.
Since the boiler was installed I have had the utter pleasure of hot showers and constant hot water for washing up. This is after years of me stoically putting up with the old combi boiler performing haphazardly, the pressure gauge dropping, and me washing up with the dribble of warm water and boiling kettles. Onwards and upwards.