Smoke alarms removed

[Paulffspark]

Hi, I am an electrician that normally works on large sites, my dad has bought a house to rent out and asked me to EIcr it. The house was built in 2003 so is in good condition, however someone has removed the mains interlinked smoke alarms and replaced them with battery ones, this is acceptable for the rental market however due to the age of the building should it have mains interlinked? And is this a breach of building regulations? Are any codes applicable? (3 maybe) Appreciate any help with this,

 

[Taylortwocities]

I assume that the house will be rented out as one whole house and not split into separate units (HMO)?

If so, then there are new regulations that landlords must provide smoke alarms
http://www.landlordzone.co.uk/press-releases/new-smoke-alarm-regulations-for-landlords
but there is nothing in the regs that say they must be mains/interlinked alarms.

Although I would always prefer those and as the wiring is already there, its a much better option for around £15 a pop.
Mains 141 Ionisation Smoke + Alkaline Battery