You're right, most alpines are spring flowering. Have a look at Silene schafta and Silene keiskei for later flowering.Also Verbascum 'Letitia', Veronica prostrata; Sisyrinchium brachypus or S. augustifolium, and Zauschneria, though this one will die in a cold winter.

Just thought of some more - Parahebe lyallii, Penstemon newberryi or menziesii, and Potentilla aurea. Just realised they all begin with P, lol!

The Creeping Phlox are very good on rockeries as well, I only planted mine last year,spreading well, deadhead after flowering and they will flower again the same year, Campanula is another,the spreading geraniums, no doubt Bamboo will come up with the proper name, my brains gone to sleep Bamboo, lol...
Helianthemum, deadhead after flowers fade and also repeats, mine was still flowering in Nov last year, started in June..

Very few true alpines flower in summer or autumn, so it all depends whether you want a rockery with all year interest in which case Bamboos suggestions are good but they are not alpines.

If you want extended flowering, you've no choice but to use 'rockery' flowering plants rather than true alpines. Watch things like Helianthemum though, and the Campanulas such as carpatica - they tend to spread, the first up to 2 or 3 feet, and the second just keeps going - slowly, but it does keep spreading. If your rockery isn't very big, you don't want something that gets too large or is too invasive. campanula muralis is at least easy to dig up and split, tends to spread out in a solid clump and doesn't have sprawly flowering shoots.

Don't forget this like mossy saxifrage and Lithodora. There is also sedums, sempervivums and some of the smaller phlox. Leucogenes grandiceps, the New Zealand edelweiss is a summer flower as are the celmisias. There is an autumn flowering gentian along with autumn crocus - in fact check out Broadleigh Gardens they have a good list of autumn flowering bulbs but thee will need some shade. We aim to have at least some colour in our garden all year round but spring is the peak season for us.

I have a south facing rockery, and there are patches of yellow stonecrop and small dianthus plants which provide a fair bit of colour throughout summer, also Sedum "Turkish Delight" which is very pretty.

I love the autumn crocus Mg and have tried many a time to no avail, haven`t a clue as to why...

For true alpines which flower later on, there are always Gentians of various kinds. Also Solidago cutleri or S. brachypus. Then there is Serratula seoanei which flowers in October. In the dwarf bulbs there is Acis autumnale.
As it is south facing I would avoid any of the Saxifrages, they dislike the midday sun ion them and tend to burn off.

You have all given the plants that I can think of! Dianthus, stonecrops, late summer/autumn gentians, autumn flowering crocus like speciosus (not the big colchicums), oh there are lots.

cyclamens too. tritellaria as a bulb leaves now flowers later though may be too tall. I've planted Scabiosa japonica var alpina, Silene uniflora and Eringium compositeum Rocky in the hopes they will provide some summer colour.

If you don't mind using annuals to fill in the gaps, mesembryanthemums offer good, bright value, especially in really hot, dry places. There are perennial varieties, too, but I have no idea what they are called.

Useful idea, Gattina. The perennials are Delosperma and the most readily available in garden centers is a yellow one called Basutoland. Pink species are also possible from alpine plant nurseries.

Thank you, Bulba! Now I know what to look for! I just couldn't understand what the guy I bought mine from was saying, and as I've moaned about before, nothing here carries much in the way of labelling. (We've just come back from our nearest equivalent to a garden centre: No prices on anything, and there were pots of soft fruit saying "Raspberry - Red" "Raspberry - yellow" and roses labelled simply "Climbing pink" and "Bush - white" We have loads of stuff in our garden with no idea what variety any of them is.

Many thanks for all your ideas. I have pleanty of plants to check out and hopefully will have a 'blooming' lovely Rockery next year!

Thanks again.

Just remember to post some photos for us to look at...