Complex sentence: Green Pond Road was a football stadium in Walthamstow, London and the home ground of Walthamstow Avenue until they merged with Leytonstone & Ilford to form Redbridge Forest, a precursor to Dagenham & Redbridge.
Split into simpler sentences: Green Pond Road was a football stadium in Walthamstow, London. This was Walthamstow Avenue F.C. 's ground for many years until they merged with Leytonstone & Ilford to form Redbridge Forest, a precursor to Dagenham & Redbridge.