ian, I read not long ago that the PIRS in the Home information packs aren't mandatory YET.
heres something I found
The mandatory documents are:
An index (ie a list of the contents of the HIP)
A sale statement (summarising the terms of sale)
Evidence of title
Standard searches (ie local authority enquiries and a drainage and water search)
An Energy Performance Certificate (EPC)
Commonhold information (where appropriate)
A copy of the lease (where appropriate)
Documents that are optional include:
A Home Condition Report (HCR)
Additional leasehold, information
Guarantees and warranties
Other searches relevant to the particular area
Do I have to put electrical certificates in my Pack?
Electrical certificates (past or present) are not a required component of the Pack, but can be included if the seller has them. Home Information Pack - Sellers' frequently asked questions