William Vallans (flor. 1578-90) was an antiquarian and a friend of Camden (q.v.) A Tale of Two Swannes is, as a poetical exercise, modelled on the lost Epithalmion Thamesis, or on the 'Marriage of the Medway and Thames' in Faerie Queene IV. ix. Spenser's reference to the lost poem is in the first of Three Proper and Wittie familiar Letters, which explains that the poem is the result of a collaboration with Holinshed, presumably the other of 'those worthy Poets'.
From A Tale of Two Swannes. Wherein is comprehended the original and increase of the riuer Lee commonly called Ware-riuer: together with the antiquitie of sundrie places and townes seated vpon the same (1590), sig. A2:
Yet hereby I would animate, or encourage those worthy Poets, who haue written Epithalamion Thamesis, to publish the same: I haue seen it in Latine verse (in my iudgement) wel done, but the Author I know not for what reason doth suppresse it: That which is written in English, though long since it was promised, yet is it not perfourmed: so as it seemeth, some vnhappy Star enuieth the sight of so good a work: which once set abroad, such trifles as these would vanish, and be ouershadowed, much like the Moon and other starres, which after the appearing of the Sunne are not to be seene at all.