I finally decided to do something about the sag in the middle of my front terrace. Jean-Pierre came with his assistance and has spent two days racking up the horizontal beam before inserting a new bit in the space. Seven centimetres of space.
Jean-Pierre claims that it is the movement of the children’s swing, hanging from the beam next to the post which is responsible, which has caused the subsidence. I don’t believe him (there is also subsidence in the nearby terrace with the jacuzzi). But to avoid having to shell out more a second time, I have ordered a stand-alone double-seat swing. Let’s hope it arrives in time for the grandchildren arriving on the 28th.