Britain’s Housing Crisis: What Went Wrong?

I hold Thatcher responsible - her first government (1979-83) started to tinker in privatization of debt. They were the ones that skuled the British in being more American (i.e. living beyond your means) and 'liberalized' the limited means of personal borrowing then in existence, thus ushering in the current usury-based system known euphenistically as 'finance'. It goes back to '81or '82. 

Absolutely, my 1st mortgage was limited to 3 x base income , overtime bonuses ect could not count. This limited the market to prices which realistically people could pay during  financial  shocks over the life of the loan.Given even then it could be very hard , my interest rate went to 15% the day I moved in. My then insurance backed repayment of the capital, garrenteed the full amount of the loan from day one, any excess profit was mine at term. Then the sillyness started , 5 times salary , assumed return rates which if not achieved would leave a shortfall. All this was to drive commissions , builders profits and estate agent fees. It was in all their interests to drive the fantasy of turning homes into commodities which would perpetually increase in value in excess of inflation . Well America should have given us all a lesson in that stupidity, however all I see is a steady pressure from the housing business sector is to make homes more affordable. That is of course only by , multi generational mortgages, shared ownership or any other way of driving real house costs and profits up, not house prices down to a sustainable level.
So what do I see now around me, every layby, bit of waste ground being used on occasion by young people living in vans. They have given up being in the system it does not work for them and never will, and unable to afford rental or house purchase no longer see any future in participation in classic social society. There numbers are increasing rapidly, two years ago there was only a couple of cans working around the island , now there is over 20, it's seen as perfectly acceptable style and way of life among the majority of there peers.

Overall I agree with the above - I am a dealer/developer. 
I have sold most of my properties as I think the UK housing market is going to "correct"
I paid £13,250 for my first house!
The amount of money the bank etc will lend is just silly if not morally irresponsible
True there is huge demand but interest rates are much higher now and people with a £400K house
with a £200K mortgage probably felt pretty secure but if the value goes down my £100K and he mortgage up by 50%
then maybe not...

Nothern Rock, Spain , US etc have all had mega problems and I believe the UK will as well although not as bad

I may be wrong but I have zero debt and no regrets about selling up...

I am not sure the boat will float as high again, the young I meet simply do not believe in the home owning dream as much and are certainly unwilling to make the sacrifices required at present. 
For example a friends son with 2 children has a very good job for around here. A very skilled marine engineer working all over the world for a major marine engine manufacturer , think container ship size engines,on a salary of £50000  a year no over time payed. His rent for an ex council 2 bed terrace house is £ 1500 pounds a month going to £2000 soon , plus rates and power bills. So he needs £26000 plus a year out of his net income. He took a cold look at rarely seeing his family working commonly 14 hour days living on board or in hotels in sometimes dangerous locations and is planning to walk and go on the dole or a local national minimum wage job with housing benefit. His college got stabbed for cash returning to the hotel in Brazil after their complaints to head office of being in a location where all the other guests were prostitutes or drug dealers, refused a move as there was to little profit in the job to move them.
So on his last job the companies Turkish division took on a engine rebuild turned down by other international sections of the business as unable to resource. Then they found out they could not resource it even by dragging in engineers worldwide  so many were walking away. So it ended up 18 hr days with a lot of the people in the team  unable to share a common language, not safe and 3 weeks of it finished him.

I didn't watch the programme, but on brightspark your question I would say signals are very much specific to the location, type of property, price bracket and individual ownership (and sometimes tenant) profile of the area. Price movements are always obscured by delays caused by this country's generally convoluted residential house sale process (and then land registry data publication lag) but here's some food for thought:

I sold a 2 bed apartment in nice part of London at end 2014. Central location, great management company, reasonable service charges. Local pop majority city professionals, high % rented, high % internationals (landlords & tenants). On sale, buyers immediately spent at least £20K on full replacement kitchen, minor structural work, full redec/carpet/radiators, plumbing upgrades. This would bring 'move in' cost to ~ £10.5K/sqm (+ stamp & legal).

The same property is back on the market. The guide price now starts from £8.5K/sqm, representing a nominal loss of ~ -20% and an inflation-adjusted loss of ~ -40% (per BoE inflation calculator). And they're not going in low; there have been multiple agents and on the market in various forms for 4+ months. So what the hell happened between 2014 and 2023?

Off the top of my head and in no particular order:
1. Tax changes impacting landlord income - reductions of allowances e.g. wear & tear 10%, mortgage interest, private residence relief 36 months
2. Tax changes impacting landlord capital gains - cgt rate increase, cgt allowance decrease, foreign/expat cgt full exemption removed 
3. Brexit - less attractive than it used to be for international professionals and their families to move here; there are equally nice countries with less admin to deal with
4. Covid - lots left for space and not quite as many came back. For those who did many don't have to be in London more than a day or 2 a week.
5. Flexible accommodation - Airbnb, spareroom, hotel tonight etc all (now) viable alternatives for flexible working patterns (compared to either purchase or rental)
6. Cost of Living - not a huge deal but definitely worth stopping obvious financial wastage on stuff you don't use/need like a pied a terre for commuting to London
7. Interest rate reversal to global financial crisis levels = the straw that broke the already very wounded and extremely downtrodden camel's back

In terms of 'missing boats', the current market price of this particular property, once adjusted for inflation, is now looking pretty damn close (<10% higher) to what I paid for it in mid 2000s when the are was much grittier and I had a mortgage interest rate of 4.74%. I guess the point is to look closely as the relative underlying factors affecting values of a property/area before placing your bets. 

Very true - there is no way I would build new now - programmes such as Building The Dream make me laugh with their costings - personally I think this is
very irresponsible by the producers. yes the UK housing market is in a mess with 2 competing factors - very high demand paid for by borrowed money with people ever more in debt - nasty...