I think there's reasonable chance that these were freight!
Doesn't matter, cigarettes are forbidden to be moved in freight, mail, or any kind of unaccompanied baggage. It has to be carried by the passenger. A whole different raft of customs regulations apply to taxable items moved as freight, in short you have to be a licenced distributor.
We used to scan all MFO boxes, freight etc at BAS... we'd let nothing through unaccompanied (and many would try mailing 1000 fags home at a time in the post, a big no-no) but we would turn a blind eye to the passengers carrying the odd extra carton or two at check in.
Of course once we'd scanned MFO's etc, we sealed them, and they went into the Movers secure yard for onward shipping. After that, it's down to the movers to keep them secure, and HM Customs to check the seals in the UK.
UK Customs have allowed us some leeway for many years now at major airheads and the seals never got checked, maybe that'll change in light of this.