In the late 1960s, UK Manufacturing Output was over 40% of GDP (Gross Domestic Product).
By the early 1900s that was down to around 15%.
It is now close to half of that.
Why is that important?
1. The less you make, the more you import.
2. You have less security of supply in times of shortage and/or war.
3. In the labour market, some workers simply do not have the ability to be upskilled to the service sector, and need the jobs that manufacturing would give, and with a reduction in manufacturing you create a pool of unwanted labour, which is persistently unemployed and requiring social welfare support. You cannot do what countless politicians try to imply is possible, and force all young people through an education system predicated on high levels of the '3 Rs'. It is a nonsense to suggest that ability to pass examinations is not represented by a normal distribution curve. In effect, the loss of manufacturing has disenfranchised a complete section of society. Struggle to read? Can't get a job, can't get a driving licence, and so on. So, far too many of the disenfranchised, who have nothing to lose, not only burden the Social State financially and economically, but they become anti-social, with each generation worse than the one before. It is a nonsense to suggest that all those without jobs can be retrained.
4. In the service sector, as more countries also make the same switch, it is a race to the bottom on prices. Wages fall, the rich get richer. Social inequality increases.
Why then, would a government choose to make reduction of manufacturing a goal? The UK government has (in effect if not by design) done so since the days of Margaret Thatcher.
A. Upper management in industry was primarily (generally) staffed by upper class idiots who couldn't organize a piss up in a brewery.
B. Manufacturing never really recovered from WW2, and desperately needed a LOT of money to modernize, and the money lenders of the City of London were not willing to lend to them. UK plc was in a REALLY bad way by 1970.
C. Manufacturing used a lot of energy and raw materials, meaning the UK would need to invest heavily in power stations, power lines, and mining. Again, there was not a willingness to do this.
D. Manufacturing is dirty (for the environment) - ask the Chinese if you don't believe that.
E. Manufacturing needs long and medium term planning, something politicians (and civil servants) are notoriously bad at.