Yes Bert's style clearly was a simple extension of his talking voice I
which I would urge all who use source singers like Bert (who may or may not be deemed a traditional singer ~ that's a different argument I think)
to do as Bert did sing in their own voice ~ and I repeat I have heard

some singers sing like him, and pick up some of his intonation/style etc

I did n't mean my earlier posting to be a criticism Dick! if anything a suggestion that singers sing in own voice and try not to try to imitate Bert
Ray