In 1909 this advertisement appeared regularly in the news section of the 'Witney Gazette', under the heading Carterton:
‘J. OLIVER conveys passengers and goods on Wednesdays and Saturdays in each week between Carterton and Oxford, starting from the Cross Roads at Carterton at 8 o’clock a.m.; back 4 o’clock, from the Old Gate House. On Thursdays he goes to Witney, starting at 10 o’clock; back from the Marlborough at 6 o’clock.’
Carterton was then a very new community of smallholders (it had only been founded a few years earlier). J. Oliver was evidently taking these folk into Oxford and Witney on market days, perhaps so that they could sell their own produce, or for them to do their own shopping.
There's no sign of any Olivers in Carterton or Black Bourton in Kelly's 1911 directory of Oxfordshire.* Perhaps J. Oliver didn't live there himself, or perhaps he had moved on to pastures new by 1911.