Rare Bird were one of those bands who went just a little overboard from time to time. They relied heavily on keyboards and the temptation was to go in the direction of pretentious a lot of the time.
They were much more popular in Europe than they were in their native UK and considerably more popular than they were in the States where they achieved almost complete obscurity, save for their second album released by ABC Records in 1970 (As Your Mind Flies By) and a worldwide hit single Sympathy, which came out in 1971.
Tonight's track is a single released off that album. Hammerhead is probably the least of the overblown production numbers, but it still manages to rely on hardcore Medieval imagery for their inspiration.
The end result gives you some idea of how wide a range the music known as Progressive was in the early 1970's and how some of it really hasn't held up in retrospect while other examples have.