>>43821
Parties do their job when they represent interests, because that's how parties become existence, that's their purpose.
When Athens fought against Persia, and they had to decide how, two parties emerged. One was formed by the landowners, those who lived from the rural lands, from gardens and herds, their interest was a strong army to field and stop the Persians before they plunder, burn, and butcher everything. The other was made by the craftsmen and traders, who worked in the city, who moved the goods with ships and sold them on far away lands, they wanted a strong navy that could face the Persians and prevent them from cutting the sea lanes. They faced a problem which they offered different solutions to, based on their differing interests. If they had a problem which threatened the interests the same, I'm sure they could come up with a solution together that would benefited everyone.
In your example the Labour and the Liberals found a common ground not wanting to close the mines, but some/many in those parties feels that isn't in their best interest so this leads to struggle within the parties. This is the problem of large "reservoir" parties that they gather many smaller groups with different interests and views.
Maybe parties should be more fluent, changing, volatile, always breaking up and reforming, to really represent the people behind them. But the tendency is that we have politicians only living from that business, who promote their own brand, which should be recognizable. Maybe never changing too - else they could be called hypocrites and turncoats, who change their mind at every two steps - or at least with the illusion of consistency.