  For a two parameter family of Askey-Wilson polynomials, that can be regarded
as basic analogues of the Legendre polynomials, an addition formula is derived.
The addition formula is a two-parameter extension of Koornwinder's addition
formula for the little $q$-Legendre polynomials. A corresponding product
formula is derived. As the base tends to one, the addition and product formula
go over into the addition and product formula for the Legendre polynomial. The
addition formula is derived from the interpretation of Askey-Wilson polynomials
as generalised matrix elements on the quantum $SU(2)$ group.
