That's what I thought, but I saw it once in a grammar book for BrE .... So is there any chance that it might actually be correct?
Yes, it's correct in a weird context. You all wake up with amnesia from drinking too heavily last night. You all try to remember what you did. Someone suggested that you planned a coup, you suggested that you organised a campaign. That's the correct, if very uncommon, usage of the past tense here. If you can't handle the subjunctive, you can say, "I suggested that we should organise a campaign".
Also, grammar books are often full of examples of what not to do. The sentences are generally preceded by a *. So you may have seen it as an example of an incorrect sentence.