What do I know about this book ? Its aimed at middle primary kids, its
set in London on the arches of an abandoned railway spur, it has
afro-caribbean kids and draws some parallels to the Hanging Gardens of
Babylon. Don't know much more about it, I read it to kids in 1994 when
it seemed rather new. Can't find it at ebay or amazon.co.uk

Hello.

I believe that you're looking for "Babylon" by Jill Paton Walsh,
illustrated by Jennifer Northway.

The description on Amazon clearly indicates that it's about some
Afro-Caribbean  kids in England.

From Amazon:

"Born in England, Dulcie is sad when she is unable to share the
memories her friends David and Leslie have of Jamaica, their first
home."
source: Amazon.co.uk
http://www.amazon.co.uk/exec/obidos/ASIN/0233973621/

"Babylon" seems to have been first published in 1982. There also was a
December 1988 edition, which may have seemed relatively new in '94.
http://www.amazon.co.uk/exec/obidos/ASIN/0099380803/

The book seems to be rather hard to find, but I've located a copy
available for  £3.00 on Biblion.com :
http://www.biblion.com/searchresults.php?bookid=40317811

------

search strategy:
amazon.co.uk advanced book search
title: babylon 
subject: children's

I hope this helps.

Thank very much - thats the one! I think I've now ordered it from
Biblion, a bit of an odd process so will have to see whether the order
went through to the supplier. Thanks again!

Thank you for the tip. 
-juggler