A political earthquake in Wales has sent shockwaves through Westminster

The most obvious conclusion to be drawn from the result of the Caerphilly Senedd by-election is that the Labour government is in deep trouble.

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That may not come as a great surprise, but even a few weeks ago, the party might have hoped for a stronger showing than the 11 per cent vote share it achieved.

Even allowing for a significant amount of tactical voting by those who normally vote Labour, once it became clear that only Plaid Cymru could stop Reform UK from winning, it is a pitiful spectacle in a constituency that has stuck with Labour consistently for over 100 years. Really, there are no excuses for Sir Keir Starmer's loss of a seat in the Welsh Valleys, once the base of Keir Hardie, the party's first leader.

The reasons for the loss are clear. There are some special factors at work as is always the case in a by-election - aside from the tactical voting. The Plaid Cymru candidate is an authentic voice, well known in the area.

Labour in Wales also has to deal with the inevitable consequences of a prolonged run in office. The party has governed the country, occasionally with minor party support, since 1999 - a hegemony unmatched in British political history outside of the long unionist ascendancy in Northern Ireland. After nigh on three decades of Labour rule - latterly marred by scandals involving a short-lived first minister, Vaughan Gething - Wales could be forgiven for wanting a change.