Saturday November 29 3:35 PM EST Gate of Hearts Proposed Round Diana's Grave By Jill Serjeant LONDON (Reuters) - Princess Diana's island grave on her Spencer family's rural estate is to be surrounded by a six foot (two-metre) high steel security fence decorated with a heart motif, according to plans revealed on Saturday. Diana's brother, Earl Charles Spencer, has submitted designs for the gates to the local planning authority near the Althorp estate in Northamptonshire, central England. Spencer plans to open the grounds of Althorp House, where Diana was born and spent her childhood, for two months next summer. Thousands of people are expected to visit the country park and a proposed museum about her life and charity work. In a separate move, lawyers representing her sons, Princes William and Harry, are to go to court next month in a bid to regulate the thriving industry in souvenir Diana books, t-shirts, coins and jewelry. A spokesman for Spencer, currently in South Africa fighting an acrimonious divorce battle with his wife Victoria, said the main reason for the barrier was to control crowds wanting to see the island, surrounded by an ornamental lake, where Diana was buried away from the eyes of the media in September. The heart motif reflects Diana's stated desire, two years before her death, to become a "queen of people's hearts." "We want to ensure it is safe. We don't want a crush on the water's edge which might lead to someone falling in," the spokesman said. Althorp House is expected to become one of Britain's biggest visitor attractions when it opens on July 1 -- Diana's birthday -- until the first anniversary of her death in a Paris car crash on August 31. Local council officials responsible for Althorp and the tiny nearby village expect about 3,000 visitors a day. But staff at Althorp expect the numbers to be much higher. "This is all so unique we simply don't know what to expect," one member of staff told The Times newspaper. Diana's tragic death at the age of 36 released an overwhelming tide of grief in Britain and has spawned a thriving industry in souvenirs. According to some estimates, world-wide sales of such memorabilia have reached 100 million pounds ($169 million) since September. The trade has prompted legal moves to ensure that Diana's charities profit from such sales. Former prime minister John Major, appointed last week as legal guardian to the teenage princes, is to apply to the English High Court next month to gain greater control over memorabilia sold in Diana's name. Lawyers say the aim is to ensure that profits from the souvenir trade go to the trust set up after Diana's death in favor of the charities she used to support -- ranging from AIDS to landmine victims and the homeless. Major needs to get court approval to pass the trademark rights from William and Harry to the charities. They will not benefit personally. Greater legal powers should also ensure the quality of items bearing the princess's name and image. "The priorities are to ensure the protection of the princess's name and to have the adequate legal moves to manage the licensing of the trademark," said a spokesman for the law firm representing Major. "In particular, we want to ensure the quality of the memorabilia and make sure the charities properly benefit," the spokesman added.