Which apostrophe?

[woodelf]

Which apostrophe would you say is correct?...a: Is that Jenkins' car?...or b: Is that Jenkins's car?...I always have trouble with this. Ta Muchly.

[albaqwerty]

Woodelf, I love puns. They can be quite impressive.

I think English is about the only language they work in.

I'm going to go and find Prefab, haven't heard their music in ages :)

[woodelf]

Good for you Alba, I hope you like what you hear again, I'm a Sprout fan missen!

[woodelf]

...and I agree with you about puns.

[tamborine]

alba, if you're going to go, I'm coming to come :)

[ChuckFickens]

↑ I hope it's good for you.

[scotman]

Things like St James Park etc touch on the nominative case.
Examples are St Andrews, Bury St Edmunds, Lytham St Annes et al which do not have apostrophes as there is no indication of possession involved.
It seems that it is just local custom whether these names have apostrophes or not.