Masterminding the reunion is 1971 skipper, John Dawes, who led the 1973 side against Penryn in a match to commemorate the contribution made by former Wales and Cardiff wing Les Williams to sport in Cornwall.
"We had a great time back in 1973 and the side I led contained Gerald Davies, John Spencer, Geoff Evans, John Taylor, Peter Dixon, John Pullin and local Cornish legend Stack Stevens," said Dawes.
"The 1971 management team of Dough Smith and Carwyn James also made the trip and we picked up some rather useful players from St Luke's College to make up our team. It was a fabulous weekend and when we were offered the chance of a reunion this weekend we all jumped at it.
"There will be a few absentees - Willie-John McBride, Mike Gibson, Sean Lynch and Fergus Slattery can't make it from Ireland and we couldn't trace Mick Hipwell - but there could be as many as 19 of the original tour party linking up again.
"It will be great to catch up on old times and no doubt we will relive a few of those great moments in 1971 when we won the four match Test series against Colin Meads' All Blacks side."
Among those St Luke's students who filled in on the day were two who went on to play for the Lions - Wales centre David Burcher (1977 tour to New Zealand) and England wing Mike Slemen (1980 tour to South Africa). Another player who filled in, although not a student, was future Wales flanker Tom David, who went on play for the 1974 Lions.
Among the 19 strong Lions contingent will be former Wales and Llanelli stalwart, Derek Quinnell. He was an uncapped player on his first Lions tour to New Zealand in 1971 and celebrated his 59th birthday this week.
In all, Derek made 31 appearances for the Lions on three tours - 1971, 1977 and 1980. He played in five Tests, winning two and losing three.
His brother-in-law, Barry John, was also on the 1971 tour with him, while his eldest son, Scott, maintained the family tradition and was a Lions tourist in South Africa in 1997 and Australia in 2001.
There will be a Black Tie dinner at the Falmouth Hotel on Saturday night and a Golf Day at Falmouth Golf Club on Sunday.
The complete list of 1971 Lions due to travel to Cornwall this weekend is:
John Dawes (captain), JPR Williams, David Duckham, John Bevan, Alistair Biggar, Barry John, Gareth Edwards, Frank Laidlaw, Stack Stevens, Ian McLauchlan, Sandy Carmichael, Ray McLoughlin, John Pullin, Geoff Evans, Mike Roberts, Delme Thomas, Derek Quinnell,. Mervyn Davies, John Taylor, Peter Dixon.