Canadian
The TUPE regulations were revisied in 2006. The regulations can be found on the BERR (Department for Business, Enterprise & Regulatory Reform) website.
"Subject to certain qualifing conditions, the Regulations apply:
a) when a business or undertaking, or part of one, is transferred to a new employer; or
b) when a "service provision change" takes place (for example, where a contractor takes on a contract to provide a service for a client from another contractor)."
Quoted from the 2006 regulations - Part 1 - Overview of the TUPE Regulations.
Having looked at the ACAS website, it appears to contradict the published regulations in this respect. However, as had been stated, both companies agree that TUPE does apply.