Hello, thank you for your question.
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If you do not intend to leave the property to a third party, you might take the view that continuing to pay six pounds per annum is the better option.
However, if you are minded to sell the property, then releasing yourself (and subsequent owners) from the obligation to pay ground rent might be worth considering. But it would still take 25 years or so to equate to £150 of rent.
Thankyou for confirming my own thoughts. It is pleasing to have a second opinion that concurs with one's own opinion. You now have my permission to go and put your own kettle on !