A raffle-style competition being used to sell an historic landmark has been slammed by campaigners.

The owner of Hadlow Tower, the world's tallest Gothic folly, announced the building was up for grabs to anyone who could correctly answer a maths puzzle and buy an entry ticket.

While many people are buzzing with excitement over the prospect of winning the world's tallest Gothic folly, others, including the Save Hadlow Tower Action Group (SHTAG), are despairing at the unorthodox sale.

A leading member of the group has called the competition "an insult."

Chairman Caroline Elcombe, already disheartened by the sale of the historic structure at less than a sixth of the price of repairs, has criticised owner Christian Tym for not getting enough visitors through the door and has now slammed the competition too.

Mrs Elcombe and others involved with SHTAG raised more than £50,000 to go towards the tower renovation.

"It’s crazy," she said. "It’s an insult to the people who have worked hard and raised the money. If he wanted to do the right thing and offer it back on the price he got it for we would find the money to buy it.

"It’s a Grade-I listed monument for god’s sake. It just makes a mockery of everything."

A spokesperson for the Heritage Lottery Fund, which awarded £2.8m in grants for tower repairs, said: "Hadlow Tower was sold to a private owner, subject to a deed of covenant being in place to ensure the Tower is adequately maintained and remains open to the public for at least 28 days a year. Maintenance and public access will still be a legal requirement for the next owners."

Despite criticism from SHTAG, entries to the competition are still pouring in with the number now in the tens of thousands.

Mr Tym said: "I can tell you it's going well. We have got a good start but we're not going to give out exact numbers.

"Whether or not it's going to keep at that rate we don't know.

"We had a lot of press coverage when we decided to sell the property but we haven't got as much this so we have been working on social media more."

So far, he estimates that 20-25% of people have answered the puzzle solving challenge required to be in with a chance of winning correctly.