I’m a big fan of putting a comma before “and” when it helps the reader and adds clarity. I read this in Metro yesterday:
“They needed a flat that was affordable but also within easy reach of work and Lewisham, with a DLR station, was perfect.”
With no comma after “and“, most of us will read “within easy reach of work and Lewisham“, get confused, and have to re-read it to make sense of it. A comma before the “and” would have solved the problem and made our lives easier.
What is the Oxford comma? It’s where, in a list of three or more items, you put a comma after the second-last item and before the “and“:
“Apples, bananas, and pears“.
Mostly you don’t need it, but occasionally it’s useful:
“I shop at Sainsbury’s, Marks and Spencer, and Lidl.” [I know that in reality M&S has an ampersand.]
The Americans are generally less keen than we are on the Oxford comma. Indeed the Maine Legislative Drafting Manual instructs lawmakers not to use it. But three truck drivers in Portland, Maine have just won a case in the appeal court that may cost Oakhurst Dairy millions of dollars in a dispute over overtime, just because of the lack of an Oxford comma.