People's attitudes to primary sector jobs have changed and they are now less attractive as they are seen as 'dirty' and are physically demanding.
People also believe there are fewer career prospects in primary industry.
People prefer the better paid, less demanding jobs in the tertiary sector which also have regular hours.
Improvements in technology have reduced the need for primary sector workers as machines have now taken over many jobs once carried out by people or animals.
It is now possible for one worker to do the work of many workers much faster.
Depletion of Resources
Many of the raw materials which used to be mined in the UK have now been used up.
Any resources left are often expensive to extract due to their inaccessibility.
This means less miners rae needed so less people are employed in the primary sector for example... in 1913 over 1 million people were employed in coal mines but now only 5,500 people are employed.
Due to the depletion of resources and the cost of mining what is left it is now cheaper to import raw materials from other countries.
For example... Port Talbot steel works uses iron ore from Norway and coal from Russia.