The British government's treatment of the Windrush migrants offers an enlightening illustration of why no-one can take their assurances on immigrants' rights seriously:

After decades in the UK, immigrants from the Caribbean are suddenly being detained and required to prove, to an unreasonable standard, their right to legally reside in the country, under threat of deportation. Downing street largely silent on the matter.

This is a PR problem for the UK's relations with the Commonwealth nations as well, but I suspect the Caribbean nations among them don't have much clout. India already knows of the UK's role in obstructing its trade negotiations with the EU due to its reluctance to loosen immigration restrictions, so this won't really change much but will, in a decade, likely be pointed to as justification for tougher clauses on immigration rights.