It looks like a variety of lantana

Thank you Andrew. Have now looked it up and yes that's it.

I read the heading of your question and it immediately brought to mind the colourful hedges we'd seen in Malta too. The yellow, orange and red flowers all together in clusters = Lantana camara, or Spanish Flag. Wouldn't be nice if we could grow it in gardens in the UK. :-)

If you have an unusually hot, sunny southwestern exposure, they should work as a tender annual, or a shrub to keep indoors in a sunny window in the winter, and plunge in the garden in the summer.

Yes Beattie and Tugbrethil. It would be nice. It's worth thinking about