UK MP Jo Cox now confirmed dead
The murder of UK MP Jo Cox has resulted in the suspension of Brexit-related campaigning so that might be the reasons. However, Carney had said the BOE wouldn't weigh in on the vote for the remainder of the campaign anyway, so it may that he just wanted to shorten the speech out of respect for the family.
Osborne is likely to do the same.
The speeches are due at 2000 GMT (4 pm ET).