4th Update: 26th July 2015

Save for the addition of rainwater goods and external decoration, the potting shed is now finished. For such a humble building it looks very impressive. The gable stones still carry a thick layer of immovable bitumen and they will not be replaced. Eventually this will weather down, but in the meantime it becomes something of a feature in itself. The original slaters had slightly shaped the upper corners of each slate, an old slating technique designed to make the slate lie flatter. Today’s slaters have replicated that technique in one part of the roof for future reference.
In the greenhouse proper all the original plinths have now been repaired using the original stone and pointed. This one repair seems to make a disproportionate difference to the appearance of the building as the sharp outline of the original structure is recreated. A new stone plinth has been built at the east end to support the new glazing bars and door, which are currently being manufactured. These had all been removed in the 1960s to install wooden doors to allow garden vehicles to be parked inside the greenhouse. That is now being reversed.
The decorators are now on site. Decoration is normally the last thing that happens but not in this case. Once the glazing bars have been scraped and metal brushed, where the glass remaining in situ permits, they are then coated with rust retardant and undercoat. This requires very delicate brush strokes to avoid painting over the glass. Once that is done, the glaziers will fit new glass where required and then putty. The whole then has to be painted again – not least to protect the putty from blue tits, which are particularly fond of linseed oil and prepared to be very destructive in their quest for it. Thus for the remainder of the project glaziers and decorators will be alternating.
The main discussion of the last few days has been on the mundane subject of keeping the drains clean. Both original cast iron drainpipes had cracked and have to be replaced. The main reason for the cracking was that leaves had blocked the pipes, which had then frozen. We are keen to avoid a repetition.
One archaeological point: the locks on the two surviving cast iron doors have now been identified as pendulum locks manufactured by J Young of Wolverhampton. Young patented this lock system in 1831. The Wolverhampton connection may support the theory that this greenhouse was manufactured in Birmingham, not London. Loudon certainly had a licensee there. There are other circumstantial reasons to be believe this to be the case and we may have found a way to prove it. That though will take several more weeks of research.