An earlier contributor to this thread described Bert Lloyd as being pleasant and personable whilst Ewan MacColl was somewhat distant and preoccupied. Actually, I had the opposite experience.
When Lloyd's book, 'Folk Song in England', came out in 1967 I bought a copy and when he came to my local folk club shyly approached him (I was 19 at the time) and asked him if he would sign it. He replied that he normally only signed books for close friends or family but he would (deign to) 'autograph' my copy - he then scrawled his name on the flyleaf. I still feel that this was an unecessarily pedantic and curmudgeonly response, especially when you consider how relatively expensive hardback books were in those days.
I should also add that he was brilliant on that particular night and I forgive him!

I also met Ewan MacColl on several occasions and always found him to be very attentive and polite. I confess to being a somewhat gauche youth, and must have asked him many stupid questions - but he always went out of his way to give me considered answers. On the last occasion that I met him we had a long conversation (about botany of all things!) and he seemed genuinely interested in what I had to say. At the end of that evening he regaled us with some fascinating stories about collecting with Alan Lomax (what I would give to have a recording or transcript of those stories!).