As someone has said it can be an advantage to extend your range as a few songs do have quite a range on them, especially those that have been adapted from dance tunes. Try Cecilia Costello's 'Grey Cock' or Margaret Barry's 'My Lagan Love', even the shanty 'General Taylor' or even the fun song 'The Irish Rover'.
As Jim quite rightly says most British source singers tend to be close to their speaking voice but that wasn't always the case. There is evidence to suggest that a century or more ago singers pitched their singing voice much higher than their speaking voice for reasons already mentioned, so they carried further. I seem to remember Willie Scott had quite a high pitch but I expect he was used to singing in roaring winds out on the fells.