The Challenger was not a big export success and the british army did not order more. The industrial base for tank production in the UK is gone as far as I know.
KMW Nexter is working on the next Leopard and I guess that britain could join the effort. I think Rheinmetall is currently offering a comprehensive upgrade package for the Challenger 2. Its rifled gun needs to be replaced in order for it to be able to penetrate the frontal armor of current tanks. I don't see a market for a new british tank. The US industry will replace the M1A2 in the not too distant future and the market will be flooded with cheap M1s.
While MBTs are not needed to combat low tech insurgents they are quite useful. Canada is very happy with the performance of its Leopard Tanks in Afghanistan. MBTs were also very effective in urban combat in the battle of Daraa in the syrian civil war.
The main problem for MBTs are drones armed with missiles and loitering munitions like Israels Harop. The battle of Idlib between turkish proxies supported by the turkish airforce and artillery against the SAA provided lots of evidence for the thesis. More recently the battle for Berg Karabach saw the destruction of ca. 70 Armenian MBTs by drones. To the best of my knowledge the only air defense system with proven good performance against such drones is the TOR. Better laser warning systems with "decoy" projection, improved bomblet protection and inclusion of tracked close in air defense systems are basic requirements for the viability of the tank battallion under contested airspace.
Britain does have a few nukes, that is it. The european militaries are in a dismal state of preparedness. I am mostly familiar with the situation of the german army but the problems appear to be similar across the EU. Legacy hardware, little maintenance, hard to get spare parts. A lot of the maintenance relies on just in time delivery instead of stockpiling. It does not work well in peacetime and it won't get better when the supply chain gets hit.

"but if future wars (the less the better) are going to be againts low tech adversaries probably in urban settings, do you need MBT's"
I think the time of low tech adversaries is over. The cost of guided missiles has come down to a point where non state actors can and do employ them. The current trend is one back to peer competiton. The US Military is transforming rapidly away from counter insurgency to peer war capability. The Taiwan strait has become something like the new berlin wall and the change of administration in the US is not going to change the geostrategic factors putting the US and China on the path to conflict. We will see something like insurgencies but they will most likely take the form of proxy wars

I think the Bren is quite a good design but I don't like the 303 cartridge, it tends to jam. I don't own a 303 rifle but the cartridge seems to be less suited for loading strips like the ones on my K98 than 8x57

Last edited by ArmouredHedgehog; 15/11/20 12:34 AM.