Complex sentence: It might be supposed that Oldham Street is so named because it links to Oldham Road but this is not the case as Oldham Street predates Oldham Road which was named Newton Lane in the 18th century.
Split into simpler sentences: It might be supposed that Oldham Street is so named because it links to Oldham Road. However, this is not the case, since the naming of Oldham Street actually predates that of Oldham Road, which was named Newton Lane in the 18th century.