Nice bike. It appears to be a Raleigh RSP or Torus which were also made in Nottingham and I'm guessing Hercules is probably a Raleigh overseas brand. Check out the RSP in my signature and you'll see that the frames are identical. If you want more info then its probably best to ask on the Raleigh appreciation thread in MTB chat as there some former factory workers there who can probably shed more light on this
Edit: I've just noticed the dropouts on mine are cut out but your ones are solid, but still the same overall shape, and mine has a wishbone seat stay where yours has conventional stays. I'm still 99.9% certain that this was made in the Raleigh factory though. Maybe earlier Raleigh frames also had the same features? The tapered tubes for the chain stays are a giveaway as you never see these on other ti frames. I think Raleigh were one of the few to build a ti frame using custom drawn tubes and majority of ti builders just use off the shelf tubing intended for aerospace use.