Here's some more info:
It will be approximately 180 feet long and approximately five feet tall. We need a very traditional formally pruned hedge to act as a fence. An evergreen ground cover will be planted on the outer side of the hedge to spill over the small slope which runs in front of the entire length of the hedge. Everything will be regularly pruned. It will have an iron gate at the entrance which opens to a long brick or stone path. The soil for the whole thing is rock-hard solid red clay. I live in a historic 160-year-old Greek Revival/Italianate home. Traditional Boxwood is our first choice if it wasn't such a slow grower. Many thanks in advance!

Still researching...
Any suggestions?
Thanks in advance!

Simplest solution is to buy more mature(larger) specimens.
You didn't mention a budget for this project.

You don't mention the depth of area you are allowing for this planting. If you have unlimited space and good air flow you might consider staggering your row, every other one two ft. forward. I've done this and the shrubs grow much bushier. A good weeping hose placed between the front and back staggered bushes gives regular watering if you put it on a timer. The roots of the shrubs have more room to spread for nutrients and water done this way. And, each 'indent' gives you a marvelous spot to tuck some color like a Miss Huff lantana which will come back every year. I wouldn't tuck something like hydrangea in the indents ...they fight to grab water from the evergreens.

I'd use hollies, but not Burfords.

Privet is an invasive exotic in NC forests. Birds eat the seeds, and then privet crowds out natural plants. I have seen 50-ft-wide privet stands deep in wild areas. It's tragic. What about American holly? It would be less work overall if you amend your hard red clay just a bit.If you can get some of the older varieties of camellia to take hold, they make a wonderful screen that blooms in cool months, and camellia would be more traditional, like your home. Go for older varieties that grow large. Many newer have been bred to stay smaller.

The all-around "tough" evergreen shrub that's a spot-on substitute for boxwood is dwarf yaupon (Ilex vomitoria). It handles full sun to shade, shade to sun, clay to sand.

For a hedge 5' tall, I'd go fro cultivars 'Nana', 'Cordeaux' (Sold under trademark name Bordeaux) or 'Schilling's Dwarf'. All of these mature 4 to 6' tall naturally.

At first the yaupons will not grow fast (for the first year for ecxample until roots establish), but then they can easily add 6 to 10 inches a year.

If you love the texture of a yew, choose plum yew instead (Cephalotaxus harringtonia). True yews (Taxus spp.) are eaten by deer. Plum yes needs partial shade and humusy soil, however.