How to expand my extended partition?

[bill purvis]

Hi,
When I installed Ubuntu on my machine, I allocated several partitions
including two within an extended partition. I now need to create additional
partitions on this disk, but for some reason the extended partition has
been truncated to the size of the two partitions contained within it.
When I did the partitioning I explicitly specified the whole of the
remaining area for the extended partition!

There's plenty of free space for the extra partitions, but all the
primary slots are occupied and the two partitions within the extended
partition are /var and /usr so I can't just delete and re-allocate.
I've tried Gparted (the GNOME Partition Editor) and fdisk (the old
faithful) and neither will allow me to extend the extended partition. 

There was a time when I would have written a bit of code to patch the
partition table, but I'm older and wiser now, and less confident of
my abilities in this area. Does anyone know of anything that can
safely extend my extended partition back to cover all the remaining area
without disturbing the contents? Then I can use Gparted to allocate the
required space.....

Many thanks,

Bill
-- 
+---------------------------------------+
| Bill Purvis, Amateur Mathematician    |
|  email: bil at beeb.net                  |
|  http://bil.members.beeb.net          |
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