HTC Desire S - UK Orange Stuck on HTC Boot logo
Here is the method we followed : 


Update the recovery to a newer version (We used TWRP 2.8)
Install a new ROM. (We installed CyanogenMod 12.1 Lollipop)
Extract that ROM and flash the boot.img manually (using ADB and Fastboot)
Boot into the ROM. 


Done !

Note : Always remember to take a NANDroid backup before you install anything to your phone !