G.,
as a lactation consultant I can tell you that while an hour nursing in not always desirable it is also not that uncommon for a new born.
I am more concerned that you describe your nipples "in tatters". This would indicate that something is not correct. It may be just not a deep enough attachment/latch - which can also really slow the feed, or it may be something else.
Your comment regarding feeling the gums clamp down indicates that a full assessment is needed. If baby is in a good nursing position his tongue should cover his lower gum and with his head tilted back slightly with chin leading and airway open the top gum should not be involved.
Please arrange a full assessment with a lactation consultant in your area (you can find one through www.ilca.org ) or at least seek a trained peer counselor through Nursing Mothers Counsel or La Leche League.
K. H.