I looked this up and found this information about it:

In its Local Plan 2040, Oxford City Council proposed installing elements from the 15-minute city urban concept in neighborhoods throughout the city over the next 20 years. These plans included proposals to improve accessibility to local shops and other amenities for residents so they didn’t have to always drive. Separately, Oxfordshire County Council announced traffic-reducing measures throughout the city, with infrastructure to encourage car travel around the city by using the ring road rather than already congested roads. Initial opposition to the plans led to proposals to introduce permit schemes to facilitate car travel at certain times, allowing car access to areas that the council planned to restrict to motorists.

First, the article says it was separate. Nobody said, "We are blocking everybody's access to this road because the goal of 15-Minute City is to restrict people and forbid them from leaving their zone."

Second, it was just traffic-calming. They put up some planters blocking roads to vehicles to encourage access by bike, pedestrians, etc. That's not restricting access, that is INCREASING access. By bikes.

They decided that a different, busier road was more appropriate for cars. How on earth does that equate to restricting access? So your car had to drive further, using a big busy road instead of a local quiet street - boo-hoo! This, to you, was a sign that the government wants to confine you to a 15 minute area and never let you leave?

Are the following measures, to you, a sign of nefarious "restricting access"?
- An ambulance can drive the wrong way down the street, but you cannot
- A bus can travel in a bus lane, but you cannot
- A commercial vehicle can park in a loading zone, but you cannot
- A vehicle with several people can travel in a special HOV lane, but you cannot if you are driving alone
- A toll bridge reads your license plate to check if you paid a fee to access that route, and charges you a fine if you did not
- The city takes out a vehicle lane to build a dedicated bike lane and plant some nice shrubs
- The city closes a street temporarily for a neighbourhood block party
- The city installs speed bumps on a quiet street
- The city builds a traffic circle at a quiet intersection
- The city puts up a sign limiting the speed you can travel
- A highway cuts through an existing quiet suburb, meaning your car cannot cross it on a quiet street; you have to use an onramp and get on the busy highway

All of those technically "restrict access" by your seeming definition. Well, at least by vehicle. Is it your assertion that private vehicles reign supreme, and if the government does anything to slow down, discourage, or increase the cost of vehicle travel, it means their future goal is to create walled mini-cities that folks can't leave?

Edit: also, you say that people threatened to hang the city council to get them to renege - are you proud of this? Your "side" is threatening to murder people if they don't govern the way they want, and that's just "being vigilant"? To prevent planters from being placed on a street? What the hell?

I don't see it as a cage at all.

I know my comment was long, but you haven't answered:

• Why you think that the same people who advocate for services within 15 minutes also advocate for confining people within a certain zone as part of that goal - have they ever said so? Why would they want to do so anyway? What do they get out of it?
• Why you think that traffic calming is a slippery slope to confining vehicles, or all modes of transport, within a certain zone, instead of just trying to balance the ease of access between vehicles and bikes, scooters, skateboards, buses, pedestrians, etc.

If you want to believe in a conspiracy, why not look at the ways in which the auto industry has suppressed other modes of transport, from inventing the term "jaywalking" to suppressing electric trams to building giant highways through poor neighbourhoods?