It was an outboard main gear with the lock about 10' off the ground and and quite obscured in the dark. The F/E would just have had a laugh with the groundcrew if he had found it, but he carried the can sadly. Dreadful practice by the groundcrew, but they do things like this, and it may be next day that you miss it 'because people don't leave things in gear locks, do they?' Always worth being aware and double checking because pilots these days do the final check of it!