I'm teaching a course on the structure of English to trainee English teachers in the Maldives.

We have been discussing stative verbs and how, in standard English, they are not usually found in the progressive tenses (i.e. We don't normally say 'I'm knowing the answer').

We have also realised that using stative verbs in the progressive is much more acceptable in Indian English and consequently also in Maldivian English. My students were very surprised to learn that in British English we don't normally say 'I'm having a headache' or 'I'm understanding the problem'.

However, we were then discussing writing postcards and how we quite often might write 'I'm having a wonderful time' - and the students asked why is 'having a wonderful time' acceptable but 'having a headache' problematic.

I don't know why! Any ideas?