Ask an Property Solicitor. Get an Answer ASAP.
Hi, in law a Freeholder can claim up to 6 years of ground rent, so as and when the "new Freeholder" comes forward, you would only be liable to him £36.
Looking ahead, you may want to try and find out who is the new Freeholder as you will need to provide this information to your Buyer as and when you come to sell.
I hope this assists and sets out the legal position.