This is an issue that was raised in another thread but I believe is important enough to have a wider audience.

Someone posting on the thread stated .....

my understanding of PRS rules is that copyright-owners' permissions aren't necessary for material used on a limited-availability production (under 500 copies).

When I queried this the gentleman concerned replied ......

I can only tell you what it says in the PRS' application form, on their website, and also what they told me verbally, in connection with 'Limited Availability Productions'.

They specifically state that permissions are not required for Audio CDs where the total number to be produced is limited to 500 copies or less. I know of several artists who have produced such CDs and they have done so on this exact premise. Here's what it says under 'Educational and Limited Availability Productions on their website:-

"MCPS has recently introduced a scheme to mlicence non-corporate audio and audio-visual productions that have a total run of under 500 copies. Although this licence allows easy access to MCPS members' repertoire without the need for obtaining permission from each individual copyright owner, there are several exclusions that apply".

I feel people should be aware that such information only applies to material registered with PRS (where PRS have effectively taken over the ownership of the copyright) and has no relevance to material that has not been registered.
In this case permissions still need to be obtained from copyright holders.