BA LHR-CPT 747 fuel leak

[PurePax]

I have received a mail from a person, not personally known to me, who reports to have allegedly been on board an aircraft at a London airport when said aircraft did start leaking fuel at a rate alarming to him.
He further says in his mail that it was apparent to him the other passengers on board the aircraft were also somewhat distressed.
He alleges the Captain of the aircraft was prepared to take off on two occasions, which, apparently caused the passengers to make their concerns regarding the supposed fuel leak known to the cabin crew. He does not say whether "prepared" is intended to indicate "willingness in full knowledge of the facts" or "ready for take off prior to being informed of the apparent problem".
He indicated that emergency services were on hand at some point during the event.
The flight apparently was bound for a Southern African country, but, according to him, did not depart on the date it was scheduled.
He didn't indicate any injuries of any nature.
This poster [PurePax] would like to note that, at night, at a possibly unfamiliar airport, it's possible for passengers to confuse the position of the aircraft they are occupying, such that they may say "at the end of the runway" when in fact the aircraft is "at the end of a taxiway", or some such other location.
This poster [PurePax] would like to make it clear that the initial version of this post was a request for information regarding the alleged incident and was not intended to slur the name of anybody involved in the incident, if it indeed ever occurred.