Well the bulkheads were all fitted back to front, but then there's not indication which way round they go until you try the side in place. Not a problem, just a few minutes spent fiddling with nuts and bolts.
The sides fitted OK on the bulkheads but there is a gab above the spaces were the bogies will go. On early railcars this was all covered with fairings but in BR days these were left off to improves access. Trouble is you can see the bottom of the floor.
Is this right? Well all the photos in books and on-lie are murky in this area. The chassis would be seen but on the prototype the spine is a lot narrower than on the model. It doesn't step back like the model does either. I suppose I can paint it black and hope no-one notices but I'm not convinced. I have a feeling that the kitmakers assumed everyone would fit the valances and didn't think beyond this.