The invention provides a process for the preparation of a multimodal ethylene polymer in a multistage process in the presence of a catalyst comprising a complex of formula (lx) wherein each X is a sigma donor ligand; each Het is independently a monocyclic or multicyclic heteroaromatic or heterocyclic group containing at least one heteroatom selected from O, N or S; L is a carbon, silicon or germanium based divalent bridge in which one or two backbone atoms link the ligands; M is Ti, Zr or Hf; each R1 is the same or different and is a linear CMO alkyl group, or linear CHO alkoxy, each n is 0 to 3; each R2 is the same or different and is a C1-10 alkyl group, C1-10 alkoxy group or —Si(R)3 group; each R is the same or different and is C1-10 alkyl or phenyl group optionally substituted by 1 to 3 C1-6 alkyl groups; and eachp is 0 to 3;