The individual aircraft has to have a supplement to the RFM that permits parachuting. In addition, you have to do it under the auspices of an approved club, which for the UK is the BPA I believe.
Rather like BS I used to do these as an extra to pleasure flying. A BPA team leader used to check out the pilots and authorise them. I remember a piece of paper added to my licence.
All of this is a few years ago. Whether EASA have generated a chunk of new paperwork, I am not sure.
It all goes back to the Article in the ANO, which says thow shalt not drop people from aircraft and is an exemption process from that prohibition.
Suggest you contact the BPA and the CAA for the current position. The BPA guys were always very helpful. If you have contacts in that game, they should know who to talk to .
Oh yes, and watch for when all the jumpers on one side jump together and PUSH off the aircraft
