What could replace Shackleton in British airborne early warning?

If the Shackleton did not exist, would Britain adopt the Canadair CP-107 Argus and use it for airborne early warning?

The Argus is possible, but the likely AEW aircraft would depend on what platform first replaced the Shackleton's maritime-patrol role.

The Canadair CP-107 Argus is one plausible option rather than an automatic answer. The Shackleton was not originally acquired as an airborne early-warning aircraft; it was later adapted from another role. The more important counterfactual question is therefore which aircraft would have filled the Shackleton's original patrol mission, since that platform would likely become the AEW candidate as well.