Invoking Brexit is no more speculative than ignoring it as if it were irrelevant. And if inferences from polls don't count as speculation, one can cite polls suggesting that Brexit mattered, just as one can cite polls suggesting that Corbyn's unpopularity mattered.
(And if we're being really rigorous, to assume that Brexit and Corbyn's un…
Invoking Brexit is no more speculative than ignoring it as if it were irrelevant. And if inferences from polls don't count as speculation, one can cite polls suggesting that Brexit mattered, just as one can cite polls suggesting that Corbyn's unpopularity mattered.
(And if we're being really rigorous, to assume that Brexit and Corbyn's unpopularity are distinct causes is itself speculative! It's plausible that a significant part of Corbyn's unpopularity came from distrust cultivated by the delayed implementation of Brexit, and from Labour's slide from accepting the Brexit referendum's result in '17 to wanting a do over in '19. A key player in the latter was one Sir Keir Starmer QC, who bounced the party toward overturning the referendum with a surprise announcement at the main party conference that no one was ruling out overturning it.)
Invoking Brexit is no more speculative than ignoring it as if it were irrelevant. And if inferences from polls don't count as speculation, one can cite polls suggesting that Brexit mattered, just as one can cite polls suggesting that Corbyn's unpopularity mattered.
(And if we're being really rigorous, to assume that Brexit and Corbyn's unpopularity are distinct causes is itself speculative! It's plausible that a significant part of Corbyn's unpopularity came from distrust cultivated by the delayed implementation of Brexit, and from Labour's slide from accepting the Brexit referendum's result in '17 to wanting a do over in '19. A key player in the latter was one Sir Keir Starmer QC, who bounced the party toward overturning the referendum with a surprise announcement at the main party conference that no one was ruling out overturning it.)