They showed up for the 5th round of the FA Cup in February 1971 (I had to check the date). I was 14 and standing in the Park Lane about an hour before kick-off, it was about half full. In those days, if you didn't get in early to defend 'your end' the away fans could get in there before you. The centre of the Paxton was full of Forest. The usual singing and chanting was going on when a large mob in red and white appeared in the corner of the Paxton and the Shelf, at first I thought they might be Woolwich, but they were more Forest. They stood for a minute deciding what to do, and then started moving along the terrace below the Shelf towards the Park Lane, joined many who were already in the Paxton.
At first there was bit of hesitation in the Park Lane, do we stand our ground, or go and meet them. Then a group started moving around to meet them, followed by more and more (I tagged along at the rear).
The terrace in front of the shelf was nearly empty at that time and the was no coppers about. The two groups faced off near the centre of the Shelf, Then a few at the front rushed at each other, followed by more. I'll always remember this Spurs fan at the front, wading in, arm over arm, like he was doing the front crawl. Forest were forced back and turned and ran back to the Paxton. Spurs fans didn't bother following them too far, we returned to the Park Lane victorious in defending 'our end'.
Oh, the game? Spurs 2 (Gilzean, Chivers) Forest 1 (?).