After waiting a week to get a response from FindMyPast re a missing street & the ref number issue & then having to prompt them for a response...I received the following last night. Oh & they've asked which street too, so it will be interesting to see if they respond to that next.
"With regards to the reference number, we’re continuing to refine several aspects of the Register, and the relocation of The National Archives’ reference numbers is part of that process. The National Archives approved removal of reference numbers from the preview of locked or unlocked records, URLs and search results to ensure protection of Findmypast's intellectual property rights."
Cheers
Carole