How old is your battery?
Are all of the connections (cables) tight and dry?

['just for fun. If you could convert the horns on the QE II from steam to electric
they still would not draw as much current as your starter.]

The "clicking" is usually a sign of a discharged battery...or poor connections.('Even in a discharged state the battery will still run all of the ancillary devices...just not engage the "Bendix" on the starter because of the
TREMENDOUS amperage draw)

You need to put a multimeter onto the battery and check the resting voltage.

'Below 12.2 volts D.C. and you're walking.