Here's the screen shot:

Have you created already one with 192.168.0.0 & not appearing?

No we were trying to change the existing 192.168.1.1 to 192.168.0.254

We have now managed to do so without error using the 3.7.8 firmware.

We would have done that first but it was not listed on the UK support page as being the latest firmware version.

Thanks to all for your help

welcome ... just to add if you are interesting ... using the Vector (vector 1 seems good) firmware with 3.7.8 will appear & a new page at diagnostics > dsl status
Here they have firmware for UK users at the end of the download page (but if the one works fine leave it as it is)
http://www.draytek.com/index.php?option=com_k2&view=item&id=5435:vigor2760n-delight&Itemid=662&lang=en#downloads
However users have mentioned slower response of menus with vector (including me but is not bothering me) with VECTOR ... seems use more memory
if you don't care about it (line stats) don't bother ... again however using the *all* file (keeps same settings) can return back firmware (between 3.7.8 "s) anytime