Robert K. Webb, 89, a longtime history professor at the University of Maryland Baltimore County who was one of the country’s foremost scholars of British history, died Feb. 15 at his home in Washington. He had lymphoma, his daughter Margaret Webb Pressler said.

Dr. Webb, who usually published under the name R.K. Webb, was perhaps best known as the author of “Modern England: From the 18th Century to the Present,” which was first published in 1968 and remained a standard college textbook for more than 30 years. He wrote several other books and was also the co-author, with Yale historian Peter Gay, of another college textbook, “Modern Europe,” first published in 1973....