i think i can see the source of all the above confusion--quote from UKBA--
This page explains whether and how you can extend your stay in the UK as a visitor for marriage or civil partnership.
If you come to the UK as a visitor for marriage or civil partnership, you are allowed to remain here for a maximum of 6 months. When you enter the UK, we will stamp the duration of your permission to stay in your passport.
If we give you permission to enter for less than 6 months, and you later want to extend your stay to the maximum of 6 months in total, you must apply for an extension - see below.
so--the applicant would need to get FLR to extend their visit to the maximum of 6 months
at a cost of
Fee if you are applying by post Fee if you are applying in person
Main applicant £561 £867
Partner or child aged under 18 (if they are applying at the same time as the main applicant in a category that allows dependants to be included) £281 for each family member included on the main applicant's application form £434 for each family member included on the main applicant's application form
hmmmm an expensive few weeks extra there-------