Ah yes, the release of the strike ridden nation from the power of the unions.
We had a very small debate on this a while back, but the situation in the early 70's, was that UK was in an economic downturn, this had happened due to the chronic lack of investment in infrastructure and R and D, and the collapse of traditional industries, where UK had been world leader. These industries at management level were complacent and failed to notice the rise of competitors like Japan and S Korea.
Think of all those great names in the fields of say motorbikes, pushbikes, cars, ships, planes, and many more, that went to the wall, not because the products were shoddy, not because the work force didn't do a good job.
The R and D aspect is summed up by our efforts at space technology, in 70 we could successfully launch an independent satellite Prospero... but it cost and needed government investment, it was scrapped as no commercial use for satellite tech could be envisaged.
Also as the effects on the economy of the end of empire began to kick in UK had joined EFTA as a way of trying to boost performance.... it didn't work hence why we joined the EU, this helped improve matters.
Then a mighty spanner in the already clunky works, OPEC oil embargo.... precipitated inflation at often over 25%.
Now if like me you were a worker at the time, and you see your 40+ hours and overtime, getting you the bare essentials of subsistence overnight, you're not going to be happy and will look to your trade union to do something about it.