Thank you for the responses so far. There is an Aikido club in my home town that says it teaches Traditional Aikido but I am not sure what that really means? Can anyone elaborate?
Your profile doesn't say where you are based, but in the UK, at least, "Traditional" is often used to mean Aikikai/Iwama (in fact anything that isn't Tomiki/Ki/Yoshinkai). It is also used by groups who have a long history of practising aikido, but aren't affiliated to the Aikikai. I have on accasion met people who say what they do is "traditional aikido" but not "Aikikai style", often with a dismissive curl of the lip as they say the latter.
There is an additional (but less common) connotation: because Morihiro Saito's first series of books were entitled "Traditional Aikido", some Iwama groups use the phrase as a kind of trade mark.
I personally don't like the description - I can't see how a martial art like aikido that only has three generations of history can be "traditional" in any meaningful way, beyond abiding by the common etiquette of Japanese martial arts...