In the case of the Vulcan, yes, though it would have been rare and I don't recall doing it.
Until Black Buck when they fitted a Porta Potty there hadn't been a bog for at least 20 years if then. I don't know if it was ever used. They may have carried a third pilot though.
The only relief was via a pee tube and woe betide the pilot that didn't check the bung before use. It used to take a long time before a new co would feel relaxed enough sitting next to someone and pee sitting down.