Conditionally format percentage value with point on two colour range

Hi

This is one of those questions that you feel daft for asking, but...
I have a column of percentage values. I want to conditionally format the column using a two colour range, so that for each cell, its colour will be where on the gradient between the two colours that percentage falls.
So if the lower colour is red, and the upper colour is green, a cell with a value of 0% will be full red, a cell with a value of 100% will be full green, and a cell with 66% will be whatever the colour value is 2/3 of the way along the gradient formed from the two colours.

The colour selected should rely on nothing more than the value in the particular cell. Not where its value falls in the range of all the other cell values in the column.

It feels like this should be easily doable. That it's such an obvious thing to want to do with percentages and a two colour scale.
I just can not get it to work...

Select cells in column. Conditional formatting -> New Rule->Format all cells based on their values->Format Style: 2-Colour Scale->Min-Type: Percent,Min-Value:0; Max-Type:Percent, Max-Value:100->OK.

Nope...
I get colours from the gradient, but the colour in one cell will change as values in other cells change - Some sort of consensus value.

I need the colour in each cell to depend purely on the value in that cell.
I've tried all the combinations of settings I can think of that look like they could work, but the wrong behaviour described above is as close as I've got.

I must be missing something really obvious. Can someone please put me out of my misery?

Many thanks.