"We don't like that finger-in-the-ear stuff at our club" was a not uncommon response to enquiries from an artist presenting traditional song in any guise. Peter was utterly uncompromising in everything he did, and the sad fact is that trad songs performed in his wildly idiosyncratic style must have been a hard sell, whoever was doing the selling."
I was doing a lot of gigs singing trad songs in the eighties and nineties,but i was able to supplement gigs with ceilidhs playing my concertina, I also played in a concertina quartet, and played in a duo with Richard Grainger mixing traditional songs with our own contemporary songs., so I suppose on reflection versatilty helped me survive.
I do remember[this was in the eighties] being told at one club not to tell jokes, and at another club that we dont have politics here.
   I encountered a different attitude occasionally, it was more we dont like concertinas, we prefer singer songwriter guitarists.so in PETERS case it may also have been occasional organisers having a dislike of concertinas.