It triggered fear
The French Revolution was regarded as appalling by English society. Edmund Burke was one of the scholars who denounced that revolution as being anti-tradition and destructive.
Radicals were among the thinkers who admired the French Revolution and longed to have a similar one in Britain. They included Godwin, Woodsworth or Coleridge, some shifted to conservatism at the end of their lives.
The attachment to the monarchy is one of the reason it was so much criticized in Britain.