Prince celebrates its 150th birthday this year, having been delivered to the Ffestiniog Railway in North Wales in 1863. The FR is currently rebuilding Isaac, a Bagnall locomotive for the L&B, but problems encountered during running-in trials mean that the loco will not be ready in time.
To fill the gap, the F&WHR will send Prince to Devon in its place.
"We're delighted to be able to help our friends at the L&B with the loan of Prince," says F&WHR General Manager Paul Lewin.
"Several of our locos including Lyd, a replica of the engines which originally ran on the line, have already visited Woody Bay.
"I think I'm right in saying that Prince will be the first tender loco ever to run on the L&B."
Details of the L&B Gala can be found here.