I think they put buzz bars on The Nash in around '81 or '82. Those trains were destroyed in the fire a few years ago so they've got different restraints now. Until then, they definitely didn't have any restraints at all.
Pretty sure they were buzz bars anyway. This image seems to back it up, you can see people resting on the bar which only dropped horizontal to the ground, and didn't drop to the knees at all.
I also remember the bars moving up before they hit a lock position. They weren't restraints as such, more like "suggestions not to get out". So CoasterGoddess' description is very accurate. It certainly reminds me of riding it in the same period.
They moved the trains around between parks a lot, so how old the trains were I really couldn't say. I saw an image the other week of Big Dipper running the trains that went to Roller Coaster (no restraints) and I think it was in the 70s. Ah, here we are:
This was in 1978. I'd posit that the old Nash trains were moved to Big Dipper in 1981/2 and the trains from Big Dipper went to the "tame" Roller Coaster over the same closed season.
I recall rumour in that period too about trains shifting between Southport and Morecambe as well, but treat it as hearsay
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