Thanks everyone for your input.
We hope this thread may have been a help to others as well who are a bit unsure of colour filters and their specific uses.
Knowing now the difference in the quality of filters we have ordered the Hoya 2" Made in Japan 81A and 82A which are both HMC multi coated and also a YK2.
We will try them out when we have some clear dark skies again. We're also looking forward to giving our new Pentax 7mm XW a first light in dark skies
Barb & David