You can do the following:
add the Land_Holder object as parameter and in the OQL query specify:
NCM.Land_Holder.ID = $LandHolder.
It seems that you don’t need to GUID for this query.
This works now, many thanks. My error was post processing of the result list which took a while to realise. This is now a really powerful approach as it allows me to create multi-table joins for a shopping basket concept.
Really appreciate your expertise and thanks for taking the time – moving forward on my project at pace now :0)