children's book series 70's - 80's

Can you help? I am looking for a series of Childrens short Adventure/Fantasy stories that involved a young boy and a black(?) cat - the name Sebastien rings a bell but I am not sure if it belonged to the boy or the cat.

I can picture the art work - more like serious comic art than softer cartoon style.
One story was about a pirate. I think the ship could fly and the captain was actually a skeleton.

Please help as I would love to buy this series as a gift for my Father as he would spend so much time reading with me when O was younger and it is to him that I owe my love for reading!!

Maybe the Tim and the Hidden People series by Sheila K McCullagh?

http://en.wikipedia.org/wiki/Tim_and_the_Hidden_People

#2 That's exactly what I was thinking but I couldn't remember the name of the books! Was waiting to ask my mum tomorrow what the books were called (My mum was a teacher and she actually taught my class when I was in middle infants and introduced me to these books).
I read them when I was in middle and top lnfants and I LOVED them. But I always just knew them as the Tim and Tobias books.
ETA If you click on the link at the bottom of the wikipedia page you can see one of the covers of the book plus it also confirms that there was cat called Sebastian (Tobias was his father).

Another possibility with a magical cat is the Carbonel series by Barbara Sleigh.

No visible Sebastians in that one though.
http://www.librarything.com/series/Carbonel

Here is a link to someone's site listing all sorts of cat books: http://www.fantasticfiction.co.uk/d/terrance-dicks/magnificent-max.htm

Oh, could it be The Midnight Folk by John Masefield? I haven't read the book, but I remember a black cat in the first few pages, and I know that he goes out of the normal world to have adventures in magic. The description mentions his great-grandfather the sea captain. The main character's name is Kay, and the author also has another book about him, The Box of Delights.

They were written in the '20s, but they're considered classic. I've never read them myself, but I loved the movie The Box of Delights when I was little, so I read a little about the books. Could this be it?

My copies of The Midnight Folk and The Box of Delights were illustrated, but not that heavily - maybe one picture in each chapter. They are chapter books, not short stories. I don't think they're a great match for the description, but they *are* great books - you should read them, gideonfrog!

I think the cat was a side kick rather than the star of the show, but thanks anyway

This might actually be the series I am looking for, thank you sooooo much. I have tried to find these for so long - my Dad will be pleased.!!

Hi Hill, I'm probably too late to join this topic, but did you ever track down the books you were looking for? The reason I ask is because I'm looking for those exact same books. I read them at school when I was a child and remember them only vaguely. Like you, I recall the black cat and the magic/fantasy theme.

I'd really appreciate it if you could let me know any info you were able to find.