how do i delete photo's in my library on my ipad? i imported them from my itouch.

Only photos taken with the iPad, copied onto it via the camera connection kit, or saved from emails/websites etc can be deleted directly on the iPad. Photos that were synced from your computer can't be deleted directly on the iPad, instead they are deleted by moving/removing/de-selecting them from where they were synced from on your computer and re-syncing.

How?

I am travelling for 5 weeks from hotel to hotel relying on wifi for internet access for my iPad.

There are no computers to use to access iTunes.

I bought a wifi hard disk as a back up for the multitude of photos I have taken both by the iPad and my camera.

So the idea is to load from the SD card to the iPad, transfer to the HDD and/Dropbox and then delete from iPad, leaving the original copy on the SD card and a back on either or both the HDD and Dropbox.

I can backup and delete photos from the camera role.

I can import the photos from the cameras SD card using the apple dongle to my iPad but these do not become part of the camera roll.

I can then back up to either or both the wifi hard disk or Dropbox

BUT, once I have backed them up I can not remove them from the iPad.

The result is that the iPad got fuller and fuller, I had to delete all my music, all the videos I had loaded to watch when there was no English TV until my iPad got too full so for the last couple of weeks there has been no backups at all except for camera roll to dropbox.

You should be able to delete photos imported via the camera connection kit via the Select button at the top right of the All Imported album if viewing the photos in thumbnail view, via the trashcan bottom right of the screen if in full-screen view. Do you not get the Select button in thumbnail view in the All Imported album ? And does that not give you a trashcan icon for deleting the photos that you select ?