I would say 100% worth appealing, you'll never know if you don't try. My DS got a pass on HTA, he only scored 84 in English, don't even ask, I've no idea at all went wrong, he's not at all bad at it usually. Anyway, I'm very thankful that obviously our headteacher has noticed his potential perhaps and had enough evidence to gain him a pass through appeal, we're very lucky. I would personally suggest what I'm going to do and (lightly, he's worked hard enough ha ha) work with him at home on sats type English work to make sure levels are a firm 5 before I may have to attend any appeals, that way you can prove that they're more than capable? That's what I'll be doing. All the best to you!
Thanks!! Has this just happened now? On this round of 11 plus? X