Northolt siege

Negotiations eventually secured the release of Walker's daughter, but he still held the child of his murdered sister-in-law hostage with a large kitchen knife.

Almost 30 hours into the siege, Walker ventured onto the communal balcony to pick up an abandoned riot shield.

Although the Firearms Wing had existed for almost 20 years, Northolt marked the first time one of its officers had opened fire, and the first use of stun grenades by British police.

Senior officers were keen to preserve the image of an unarmed police force and often prohibited the overt carrying of weapons.

D11's capabilities were not widely publicised, even within the Met, and officers responsible for managing major incidents often did not hold the unit in high regard.

Further, the Northolt siege took place less than three months after a black woman was accidentally shot and paralysed in Brixton, South London, during a police raid on her home by officers looking for her son.

After a domestic incident which left her requiring hospital treatment, Marlene took their daughter to stay with her sister, Jacqueline, in her flat at Poynter Court in Gallery Gardens.

Walker visited Marlene and the four-year-old child multiple times over several weeks but was refused entry into Jacqueline's flat.

He returned her to Gallery Gardens the following morning, Christmas Day, and ordered her to collect their daughter but instead she went to a neighbouring flat to call the police.

A few minutes into the negotiations, Walker slashed and stabbed Jacqueline multiple times and pushed her out of the front door onto the balcony.

They brought Marlene to the window; Walker attempted to drag her into the flat and became further enraged when she managed to resist him.

He repeatedly held the children out of a rear window, threatening to drop them, which prompted firefighters to set up blankets underneath in case it was necessary to catch them.

At one point, he cut the girl's hand and dangled her over the balcony, causing her blood to drip onto the firefighters.

By the evening of Christmas Day, Walker was demanding the police bring him Marlene in exchange for the girl.

[11] Two armed officers threw stun grenades through the windows of the flat, knocking out the lights and leaving debris strewn across the floor.

It later emerged that, of the first two shots, one had missed and one entered Walker's armpit; the third impacted his shoulder and ricocheted into the side of his head.

Its conclusion took place in front of a crowd and was captured by television cameras as the incident commander had been giving a press conference at the moment Walker appeared on the balcony.

Smith also felt that it demonstrated that not all incidents could be resolved by negotiation, and that D11 presented a "viable alternative" in such situations.