For once, you've visited a location that I'm very familiar with! I visited Chepstow Castle back in 2003. It was part of a location tour I took when I went to a Robin of Sherwood convention (Silver Arrow 2003). As you've probably guessed, Chepstow was an RoS film location. Anyway, I think you took some wonderful photos! As stonepicnicking_okapi said, the weather makes the castle look atmospherically gloomy. :-)