Linguist Richard M. Hogg, general editor of The Cambridge History of the English Language, also wrote the study A Grammar of Old English, a work in two volumes, Vol. 1: Phonology and Vol. 2: Morphology.
Both volumes of A Grammar of Old English have recently become available to University of Illinois users as e-books provided through Wiley Online Library. You can access Vol. 1: Phonology here and Vol. 2: Morphology here.