I've looked this up in CPAG which refers to para BW2 Annex B para 13 GM.

What is this please ?

It's the Housing Benefit Guidance Manual.
The relevant paragraph states...

"Any income in kind e.g. concessionary coal, food, cigarettes, or petrol for personal use, except provision of support under the immigration and asylum act."
"HB sch 5 para 23, CTB sch 4 para 24."
"Note: Payments to a 3rd party that reach the claimant as goods or services are not disregarded as payment in king , but are taken into account as notional income."

Annex B is headed "Other Income - Items to be Wholly Disregarded.

Thanks for that John. I was a bit flummoxed

What about food vouchers and their effect on IS? After all this would be the ex paying a 3rd party (the shop) for vouchers which could then be exchanged by the claimant for goods - or am I being far too pedantic?

I need to be sure as one of the hostels is advising their residents that food vouchers are ignored for IS purposes.

Decision Makers guide para 28418 covers this, with the following advice to DWP decion makers

"The DM should fully disregard any income in kind except
1. support provided to a claimant under specific immigration and asylum law and
2. notional income and
3. income paid to a claimant or member of the family because of involvement in a TD and
4. payments made to a third party in respect of the claimant which are used by the third party to provide benefits in kind to the claimant."