As someone who worked at BG, the depot hasn't closed. It lost its allocation in late 1987with the remains units moving either to NL or the razor blade factory. The 350s had already moved on to YC and KY. The depot was relegated to light maintenance and fuel, the fuel and repairs and is now back to doing light maintenance, some light exams and fuel. The depot is now a former shadow of its self just having two covered roads which where the old stop roads. It under go some refurbishment a couple of years ago.
When the brass came to look at BG at the introduction of 14x and 15x units they were quite amazed at the size of it but said that two156 wouldn't fit in the shed, and that NL would get the work , the repair shed at NL was then found to be too short and had to be extended.