@mathsman:
I don't know how the syllabus is designed, but I would think it right to assemble a group of leading professionals in various non-academic careers - architects, accountants, engineers, scientists, journalists, shop managers and the like - to establish between themselves what is the best blend of basic mathematics for pupils not yet ready to decide on higher-education and career choices.
At up to GCSE Level.....
Obviously money is a priority for everyone and anyone, including those listed above, so I would add a thorough grounding in percentages and loan / debt calculations to the basic money arithmetic; including understanding what the words mean and how to realise when the lunch is not free. (e.g. to avoid tricks like 'Buy Now - Pay Later' and the nature of credit-card purchasing).
I would also add simple Statistics - at GCSE Level not necessarily things like Standard Deviation but averages and means, and with particular reference to understanding the crucial difference between Risk and Hazard, and the compounding effects of % on statistical counts.
Plane, and simple Solid, Geometry - basic geometrical rules, and Trigonometry, you can use for all sorts of practical purposes in all manner of different fields.
Areas and volumes - circular and trinagular as well as rectilinear.
Algebra - introduced early, not so much for its own sake beyond its own rules as necessary, but as a tool in much the same way knitting-patterns, chess notations or cake recipes are short-hand instructions - with the bonus that the rules allow you to customise the instructions to the task. So early understanding of simple algebra can then be used in the other topics, to show it's not merely a puzzle thing that terrifies everyone with its weird x.
Graphs - line, bar, column, also polar, for added interest. A practical application for these is the tachograph, such as used in the school buses; and indeed a sample tachogram formed questions in the GCSE exam I took. Graphs showing simple algebraic equations, as well as the sort of non-linear graphs given by statistical studies like age-ranges and the weather. The trigonomentrical graphs - it's possible to show rather elegantly, the relationship between sin & cos, the triangle and the circle, graphically.
Basic Theoretical Mechanics - as adjunct to qualitative studies in Physics. The lever (a neat algebra illustration of the [ab = cd] type), inclined-plane and its screw-jack equivalent; simple planar force diagrams and how they are used daily in various areas of work. I'd leave circular motion to an more advanced level though it's not especially hard.
Further co-ordinates - introducing (x, y, z) as Ordnance Survey points. (NGR and altitude). No need to delve deeply into the abstractions, but it illustrates you can count in 3 dimensions and a map of real countryside is a very good introduction, especially if a local example is used. (When I tried A-Level Physics, at school, the local brickworks chimney was the object at infinity for telescope studies. It was about a mile away, near enough infinitely far for an optical-bench telescope!)
I think that lot would be a pretty good start!