pbr Five years on from the terrorist attacks on London's public transport network, survivors and relatives of victims are to assemble at a series of informal memorial gatherings to remember the day's events and the passing of loved ones.br ppbr 52 people were killed when terrorists launched a series of co-ordinated bomb attacks at three London Underground stations and on board a double-decker bus in Tavistock Square.br ppbr Transport for London has invited those directly affected by the bombings to mark the time of each attack on the platform of each station.br ppbr A permanent memorial to the victims of the bombings, known as the 77 attacks, was unveiled last year in Hyde Park.br ppbr It features 52 stainless steel columns, representing each of the innocent dead. The pillars are inscribed with the date, time and location of each of the four bombing sites.