We got Andy from the local MOT garage to come up and have a look at our welding. Promisingly he said that the welding was ok - good for first time welders! Some of our earlier efforts could have been burnt in a bit more, but will still suffice.

The bad news was that the sills weren't in good shape and we should consider replacing them. Not news I wanted to hear. The prospect of taking the sills out is a bit scary so we'll have to mull over this news and think about what to do.