As MrM points out, there were several A Level (and for that matter O level) exam boards and syllabi at that time.
I too would be curious to see some of the papers I sat from the 1980s.
You may be interested to know that we studied a Modern Maths syllabus (moderated by the School Mathematics Project) at my school - for my
O Level exam (not even A Level!) we had to learn:
matrices and vectors including multiplication of rectangular matrices of various sizes
determinants and matrix inverses of 2x2 inverses
use of matrices to represent 2D transformations - rotations, reflections and shear
modular arithmetic
groups - basic group tables and knowledge of the axioms
converting numbers between different number bases e.g. decimal and hexadecimal or base-5 to base-8
basic set notation - inclusion, is-an-element-of, subsets, empty set
basic topology - Euler's formula for polygons (and possibly polyhedra)
logarithms
I can also remember in class that we looked at the Fibonacci and Farey sequences, and tessellations of various shapes.
For the SMP A Level there was a strong focus on vector techniques in kinematics, and the standard A level syllabus included complex numbers.
I had a look at some Further Maths papers from a traditional syllabus at the time and they included questions on partial differentiation!
There's definitely an assumption now that teenage students are incapable of studying anything vaguely interesting or out of the ordinary