P.1154 fighters would still need airborne early warning

Why would the British task force take Harriers if it already had P.1154s?

It would take the P.1154s, but changing the fighter would not solve the lack of airborne early warning.

If Britain had developed the P.1154, it would have taken that aircraft to the Falklands instead of the Harriers. The fighter substitution alone is not expected to change the outcome greatly. The central limitation identified is the absence of airborne early warning, which a different fighter would not automatically provide.