Mr Hayman was assistant commissioner at the Met on 7/7
A former counter-terrorism chief wants an independent public inquiry into how four Leeds-based suicide bombers were able to attack London on 7 July 2005.
Andy Hayman, assistant commissioner at Scotland Yard at the time, said without an open inquiry "no-one can be sure if key issues have been missed".
The comments come in his book, The Terrorist Hunters, extracts of which are published in The Times newspaper.
The bombers and 52 people died in the blasts on London's transport network.
Mr Hayman wrote: "Incidents of less gravity have attracted the status of a public inquiry - train crashes, a death in custody and even other terrorist attacks.
"How can there not be a full, independent public inquiry into the deaths of 52 commuters on London's transport system?
"There has been no overview, no pulling together of each strand of review - no-one can be sure if key issues have been missed."
Survivors and relatives of the 7 July victims have taken their fight for a public inquiry to the High Court following last month's publication of a report by the Intelligence and Security Committee (ISC).
The report exonerated the security services of any blame for leaving Mohammed Sidique Khan, the ringleader of the 7 July attacks, free to plot the atrocities.
The bombers were Khan, from Leeds; Shehzad Tanweer, born in Bradford and living in Leeds; Germaine Lindsay, from Huddersfield, a convert to Islam, who moved to Buckinghamshire; and Hasib Mir Hussain, from Leeds.
The government has consistently resisted calls for a public inquiry into the bombings.