public void ChangeColour(Colouration.Colours colour)
    {
        // TODO: Call ChangeObjectColour(itemheld[if not null])

        // Activate/deactivate colourised GameObject instances
        foreach (var g in colouredObjects)
        {
            g.GetComponent <Colouration>().ReactToLight(colour);
        }
        // Change scene lighting -- stub code using GameObjects (UI panels pretending to be filters)
        redLight.SetActive(colour == Colouration.Colours.R);
        greenLight.SetActive(colour == Colouration.Colours.G);
        blueLight.SetActive(colour == Colouration.Colours.B);
    }
    public void AddLens(Colouration.Colours colour)
    {
        int insertionIndex = 0;

        switch (colour)
        {
        case Colouration.Colours.R:
            insertionIndex = 0;
            break;

        case Colouration.Colours.B:
            insertionIndex = 1;
            break;

        case Colouration.Colours.G:
            insertionIndex = 2;
            break;
        }
        colourWheel[insertionIndex] = colour;
        ApplyCurrentColour(); // In case the lens is added to the currently active slot.
    }