During our May trip to England, we spent 4 days in Oxford and stayed near the museum of natural history.
We found Johnson's laundry service in the Jericho neighborhood, which was within walking distance of our hotel.
They were very nice. They provided a large, zippered bag for our laundry. (Made of paper cloth, like the kind that lots of reusable grocery bags are made of.)
They had everything washed, dried, and folded, and returned in the zippered bag, which we were able to keep. In before 10am, ready at around 4:30. I think the price was Ł27. They initially said that same-day service was Ł30, but at pickup they only charged Ł27.
Pricier than most, but lots less expensive than hotel laundry. I would use them again.
(P.S. Jericho is a great neighborhood to explore in general!)