This page of the Watch Dogs Legion guide contains a map showing the locations of all tech points found in the City of Westminster.
There are 21 Tech Points in this district. The majority of them are located in restricted areas, which means that getting them can be risky. The points are located in the following places.
Vauxhall Bridge [1]
The Tech Point is located under the bridge. There are two cages, in one of them you will find a hole - deploy the spiderbot and enter it. Inside, there is a hole obstructed by a barrel which leads to the room with the tech point. To go further, you must destroy it, for example, by detonating a nearby trap.
Perry Harris Redevelopment [2]
The technology point is located on the barrels at the lowest level of the construction site. You can easily sneak in there with your spiderbot.
Lambeth Bridge [3]
The target is located in a room below the bridge. It's locked from the inside, so you have to sneak the spiderbot in there.
Wellington Arch [4]
You need to get to the roof of the tower. The Tech Point is located under the floor. Use the collapsed floor to get the spiderbot into the ventilation shaft and reach its destination.
Buckingham Palace [5]
The Tech Point is located on a table opposite the guard room near the main entrance to the building. You need to distract the guard patrolling the area.
Broco Tech [6]
The Tech Point is located in a ventilation shaft next to the main entrance to the building. You need to use the spiderbot to get there.
Westminster Abbey [7]
Reaching the target requires the use of a cargo drone. The Tech Point is located in a pot on the roof of the building adjacent to the courtyard.
Downing Street [8]
The Tech Point is located on a table in the central part of the courtyard. There's an alarm camera right next to it. If you don't want to sneak, you can just fly in on a drone.
Admiralty Arch [9]
The Tech Point is located at the junction between the two buildings of the complex. You can get there by flying in by a cargo drone.
London Carriage Service [10]
In this case, finding the tech point is not so easy. To get it you need to reach the underground part of the complex. You can do this through a small office located next to the round tower. Inside you'll find alarm gates and a security guard. Deactivate them and aim your weapon at your opponent. He will escape, and you will be able to operate freely in the room.
Now activate the spiderbot and place it on the shelf under the ceiling. That way, you'll get across to the other side and open the door. You have to go directly into the complex, because in the area of question you have to throw the spiderbot to an elevated area in order to get to the ventilation shaft.
Canadian High Commission [11]
The target is located on the roof of the building, under the stairs. Fly in with the cargo drone and then use the spiderbot to get to the target.
Regalia Theatre [12]
The Tech Point is located at the connector between buildings. You can get there with the help of a cargo drone or by using the lift (you need to lower the posts on the road and bring it to the area).
Palace Of Westminster [13]
Technology points are located on the balcony of the building. Just fly over there with a drone.
Chinatown [14]
The tech point is located in a restricted area. In the courtyard there is a storage room surrounded by a net. Use the spiderbot to get inside (there is a hole in the fence).
New Scotland Yard [15]
The tech point is on a table on the floor with the guard room.
Buckingham Royal Mews [16]
The tech point is located in the interior of the building - in the room next to the garage door.
SIRS HQ [17]
The tech point is located in a locked storage room upstairs. The terminal unlocking the door is the next room. You can fly there by drone or climb through lower floors located at the entrance to the guarded area.
Covent Garden Piazza [18]
To get this tech point you need to use the spiderbot. At the entrance to the restricted area on the south side there is a marketplace. Find a wooden wall with a hole in it. Deploy the spiderbot there.
Buckingham Palace Gardens [19]
At the back of the palace you will find a terrace. The tech points is on one of the tables.
Throne's Felts [20]
The Tech Point is located in the interior of the building - at the very bottom under the stairs. The easiest way to get there is with the help of a spiderbot.
Somerset House [21]
The technology point is located under the floor of the facility. Deploy the spiderbot and travel behind the stage. There's a broken grate under the stairs. Go in there and you'll reach the tech point.