This is from RT, which is apparently a Russian television network so it's obviously suspect (emphasis added):
Secret files detailing the shadowy Middle Eastern business activities of Sir Mark Thatcher, son of the late former Prime Minister Margaret Thatcher, will be kept under lock and key in government archives instead of being published as expected.
Four batches of documents on the younger Thatcher are being retained despite official legislation dictating documents should be released after 20 years unless there are good reasons to retain them in Britain’s National Archives. ...
Two further files have been designated as "temporarily retained" and have been assigned no date for release. These are titled ‘Mark Thatcher and the Omanis; other allegations against Mark Thatcher’ and ‘Request by Electronic Data Systems to employ Mark Thatcher.’
It is thought the files pertain to Middle Eastern construction contracts and a role Mark Thatcher took up at the US Department of Social Security while his mother was still in high office.Of course, it's also an extremely stale story if it's any story at all.