Is Buildings control required when upgrading fire alarm system and smoke detectors

HMO Licensing

Hi there
I am in the process of remortgaging my HMO property which we bought 2 years ago. It was a residential house previously and we did some renovation work listed below.

Added a new bathroom. Converted the ground floor living room into two bedrooms by reinstating a partition wall (not load bearing) between the two rooms and reinstating the original doorway for separate access to both rooms. This would have returned the downstairs lounge to it's original design as two separate rooms. Finally we installed an A rated fire alarm with smoke detectors in all rooms, emergency lighting and break glass on every level. We also replaced all doors with fire doors, with smoke strips and door closetrs as per the HMO officers guidance.

When I did the renovation I worked closely with the local HMO officer and they were happy and provided an HMO licence.

As far as I am aware none of this work requires sign off from building control. However, The new mortgage company is asking for buildings regulations for the fire alarm we fitted for the HMO license.

Can you kindly offer advice as to weather upgrading the existing smoke alarms to an A rated fire alarm system would require Building control to sign it off? And if so how do I best proceed.

Thanks in advance
Best
C