Thanks Gerald for your info.Yesterday I purchased two filters by Baader, the 2" Contract-Booster and the IR Blocking Filter. The last on the list for me to purchase is Orion Skyglow Broadband.
The image show the way I do things. The 'thing' on the left goes in the focuser, inside that one filter will fit. On the right is the T-ring, which fits in the ' thing' on the left, should I need to double up two filters, inside will be space for the second filter. With a few dollars spent on a bit of machining it will be Honkey Dory. What made me buy the filters was the excellent article on the web:
www.ayton.id.au/gary/science/astronomy/ast_light_pollution.htm
The information on page 6 goes right to the point about filters without any waffle.