Thanks Anne, I think you're right! I've done a couple of searches for Bayel glass - something I had never heard of, but then I don't know much yet! I've found a couple of bowls with exactly the same kind and colour of blue streak, one much more oval and another one narrower but still a bit wider than mine, dated 1950-55. There was also an oval bowl with a grey centre which looks rather like the other bowl I posted on the message board at the same time as this one. Most Bayel glass seems to be wine glasses and clear crystal, but there are a few of these streaky art items out there.
So much to learn, so little time . . .