Let Ξ be a one-relator group
with presentation ℛ = (x1,⋯,xn: Rp) where R is not a proper power and p ≧ 2.
Then given any integer q, relatively prime to p, we can construct the Lens
space ℒ(p,q) for Ξ from the cellular model C(ℛ) of the presentation ℛ by
attaching a 3-cell via the attaching map Rq− 1, which generates the ideal
ZΞ(R − 1) ≈ π2(C(ℛ)). In this paper we classify these Lens spaces up to
homotopy type. We also discuss the non-cancellation aspect of these Lens
spaces.