Thanks Colin, Although I was able to login into any APs however none of the command line commands were affecting any of the APs using SSH. It showed that it has sent the command but nothing happened.
All the digitally signed images/firmwares either 6.5.2 or 6.5.3, none of them works with some of the IAP-205s (Taurus). Strangely enough out of 16 205s only one accepted the 6.5.3.
So today I unplugged all of them, reverted to 6.5.2 by only plug-in two APs (both 205s) and it didn't work. So I reverted another step back, this time to 6.4.4.xx. This however worked straight away. So it seems like there is some issue with 6.5.xx version firmware.
Now I have 18 APs out of 21, Taurus (205s) and Hercules(325s) APs working but not Pegasus. So I have brought the Pegasus into another network. Will try and push the 6.4.4.xx image and will take that back into work on Tuesday.
I'd like to thank you for all your support and efforts. You're truly a Gem!
Many thanks
Kindest regards
Jehanzeb