From what I can see fishing rods are not specifically mentioned in the baggage essentials area of ba.com which is strange given it's a more popular leisure activity amongst the British than the likes of diving and surfing.
I never used to have a problem carrying my rods on board with me but that was back in the good old days. Now I just carry telescopic rods in my checked luggage.

You'd be awfully unlucky to be charged extra if you're inside your weight allowance however it would be interesting to find out.