It is an interesting question that I have encountered preparing my dissertation last year.

The protection of individual rights and freedoms is a cornerstone of British liberalism that even hard-line Tories shyed away from tampering too much with. Of course the sympathy reserved for someone like Marx and other radicals was different from that reserved for people that were more in line with the moderate stance of the British government. It is however reasonable to think that there was a genuine support in the British middle class for the upholding of these principles, as is possible to gather from informations about charitable subscriptions in the press.

This type of humanitarianism fit really well with the Victorian vision of being the pinnacle of civilized society and the polar opposite of what was considered continental tyranny.

Of course it is hypocritical how this mindset largely did not extend to native colonial subjects but on British soil continental revolutionaries did enjoy a basic level of tolerance and, depending on the popularity of their cause, even support from different strata of society and lived in one of the arguably less policed societies in Europe.

If you wish to read more in general about the Victorian approach to humanitarianism I suggest Caroline Shaw's "Britannia's embrace". If you are interested in a case study, Elena Bacchin in "Italofilia" describes quite in depth the reception and stay of some revolutionary Italian refugees. I think there is an English translation of the latter book but I am not 100% sure.