If people are still looking for clarification on this point there is a thread in the Stickies that addresses it:

Quote:The Manx Grand Prix is not inscribed with the FIM as an International Non Championship meeting. The MGP is permitted with the ACU and inscribed with the UEM as a "European Open" event.

Therefore as a UEM "European Open" event only riders with a licence issued by the federation of a European country are eligible to enter the event, ie ACU and SACU licence holders must have held as a minimum a National Licence issued by the ACU or the SACU for at least six months prior to the first day of practising on 20th August.

Competitors from other Federations within the UEM must have held as a minimum a National Licence issued by their FMN for a minimum of six months prior to the first day of practising.

For clarification and information, riders with a licence issued by a federation outside of Europe should contact Caroline Etherington, Race Secretary by email mgp@manx.net or phone +44(0)1624-644649.

Basically an International Licence does not automatically get you into the meeting, you need a licence issued by a European Federation member. So, non European riders, you may feel the Irish or Dutch federations are more rider friendly than the ACU, I couldn't possibly comment.