After all, one of the Cons' first strategies to control committee proceedings (as contained in their dirty tricks manual) was to exercise strict top-down control over witness lists:
Last year, the governing Conservatives prepared a secret handbook on how to disrupt parliamentary committees and create chaos. No mere pamphlet, the book ran to 200 pages.Nothing seems to have changed since the Cons took a majority in Parliament: they've continued to dictate who they want to allow to testify while shutting out anybody who might have anything inconvenient to say. And indeed, it was just last year that the Cons made a coordinated effort to institutionalize secrecy as to how witnesses were selected.
It instructed committee chairmen to select blatantly biased witnesses and tutor them in advance.
So barring some rather compelling evidence to the contrary, the general rule looks to be that witness selection is just as much a matter of party control as anything else the Cons do.
At the very least, that should create serious doubt about the Cons' story that their own witnesses are being chosen through a haphazard, second-cousin-of-a-constituent-who-heard-of-a-guy process. Which is the closest to an excuse they've offered for singling out hate groups to talk about immigration - conceding utter incompetence on the part of one MP in order to try to escape questions about the entire party's sympathy for bigotry.
That itself would create reason for criticism. But there's reason to be skeptical of the Cons' cover story - and the more control they continue to exercise over witnesses and how they're chosen, the more reason there will be to doubt that their choice of immigration witnesses was really a matter of one MP acting alone.