There are at least two underlying issues effecting UK politics which have adversely affected national standing.
The first is BREXIT which has damaged our economy and how Europeans perceive us. I make no excuses for my views on Brexit and how it was implemented by self interested short sighted mainly right wing snake oil salesmen. The only beneficiaries have been Russia (seeing a divided Europe) and to a lesser extent China. None of the claimed improvements in our nation's standing have come to pass.
The second is our electoral system (FPTP) which gives rise to polarised divisive politics of extremes with governments rarely voted for by a majority of the people. I lnever voted for the winning candidate where I live so my vote never counts except to add to statistics that expose unfairness.
Our system allows government to virtually ignore those who don't vote for them and only pay lip service to actually considering the common good. This in turn results in apathy to politics and worse still drives some to support extreme of left or right.