Folks may scoff at that strange, quirky, historical Harrier INS but when it was first introduced there weren't any other fast jets that could operate out of forward locations with no runway. In fact, there still aren't. The idea was simple enough - flying out of forward areas right up with the infantry, Harriers needed to operate with minimum ground support, only what could be flown in by the mighty (?) Westland Wessex. So no heavy fuel bowsers, GPUs or crew busses etc. Aircraft sat there under their camo nets, cold and dead until needed in a hurry. Rather than wait twenty minutes for the contemporary "steam driven INS" to align itself before the aircraft could fly, the INS could be aligned as fast as a pilot could get aboard by using a portable inertial unit. This was kept running and aligned in the support tent (for detachments that actually had the luxury of a tent). Technology has moved on and the system now seems quaint and silly, but at the time it was considered a pretty nifty idea. RAF Harriers were not, of course ever intended to go to sea in a carrier. No wonder they had problems on a heaving rolling moving deck. So, whose brilliant idea was to do away with the Sea Harriers in the first place? Probably the same people who later took the credit for the success of the Falklands campaign (Succesful from a British viewpoint that is)...
