There seems to be a problem for some about the validity of my above post so I will give you a little more info on my recent experience.
Received the under consideration stamp and informed of the house visit, would need to produce two witnesses no problem.
Police turn up do their thing and leave after saying everything was fine.
Next day wife gets a call from the IO from window 2, Korat asking us to bring in another witness as the two old girls we presented were related, ie, sisters but no relation to my wife. Different blue books and all.
We took another lady into the office and was assured that all was in order, again.
Just the luck of the draw but how they interpret the rules is a mystery to me.
The same two original old girls were my witnesses five years ago on my first Non O extension.
Go figure.