Johan, I’m a B&M fan and I also own GP7 no. 1555. I had it converted to PS 3 earlier this year.
if you’re not already a member, I highly recommend joining the B&MRR Historical Society. For a modest fee, you get four well done magazines, four newsletters and a calendar each year. They have also sent me three free B&M books over the years I have been a member. B&MRRHS membership is a great value!
John