Raiding the demotic: verse as evidence for speech prosody in Old and Middle English

This article reviews the isomorphism which may or may not have existed between the speech-prosodic principles pertaining in Old English (OE) and in later Englishes, and the metrical patterns evident in both OE and (early) Middle English lyric poetry. A key question is this: was there isomorphism in OE between rules of right-edge phrasal prominence in speech and purely metrical prominence? Recent theories of OE metrical prominence, particularly those of Russom (2017 and earlier works) show that many normative OE half-lines have a structure which can be adequately described without making reference to right-edge prominence. That very adequacy is a challenge to metrists since well-known eurhythmic phenomena of promotion (of erstwhile weaker syllables to relative stress position within the verse line) and demotion (of erstwhile stressed syllables to relatively less-stressed positions) depend crucially on phrasal right-headedness: if that right-headedness didn't exist in OE, where did it originate? And if it did exist in OE, why didn't poets then make use of the metrical opportunities the language afforded? What can revisiting and studying isomorphism (or the lack of it) between the forms of language and of verse teach scholars about English poetic history?