Carl goes on to add "and flat". Carl posts that he didn't know when pressure vessels and thereby the possibility for carbonation were introduced for beer, but he suspects they didn't exist then.
Perhaps I can shed some light on several of these areas. As for carbonation, the Celts and Brits had the same pressure vessels as did the Burton brewers who shipped IPA around the world. They are called "Barrels", and the coopers' art was well established in the British Isles before the Roman Invasion.
It had not been forgotten during Henry's time (The Renaissance), since it was the vessel of choice of both the Burton brewers of IPA as well as the modern day Real Ale advocates of CAMRA. The carbonation was less than Bud, but equal to today's real ale served in England. For a killer head the Norse (and probably more than a few Brits and Celts) would plunge a hot poker into the mug to release dissolved CO2 and produce accompanying foam. At a time when central heating was unknown, the alcohol and actual warmth of the drink were probably welcomed.
OG of medieval beers would have been at least 1.070 to insure a reasonable shelf life. Spoilage was delayed by the higher alcoholic content. FG could not have been much higher than what we would have today from such a beer, or the preservation effect would have been nullified. Please note that guidelines for a number of today's brews (barley wine, English old ale, Scotch ale, imperial stout, several Belgian ales, bock, doppelbock) may have an OG which exceeds that of the Medieval brews.
As for flavors, the Medieval brewer did not have any black malts or crystal malts. The black malts were not available before 1817. Colored malts resulted from uneven heat control which would have produced pale, amber and brown malts in the same batch, and likely in random distributions. Brown malt was also intentionally produced to reclaim slack malt.
Whether the Medieval beers were cloudy is open for debate. Young beers would have had a higher degree of cloudiness than beers which had been aged, just as today. An aged ale commanded a higher price during the middle ages. By the standards of AB (St. Louis, MO) probably most real ales are cloudy. Try to pour a crystal clear glass of Th. Hardy's ale. Not until glass became the common drinking vessel did beer clarity become much of an issue.
Most English ales brewed before the 16th century would have been unhopped. It is hard to say with any certainty that none were. Hops were introduced into England by the Romans who valued them as food. Since all manners of herbs and spices have found their way into beer, who can say that someone in Medieval England did not use hops in theirs? Documentation identifies sweet gale, marsh rosemary and millfoil as herbs used as gruit in Medieval beer. That is about as complete as saying only pale barley malt, ale yeast, Cascade hops and water are used in modern beer.
Certainly ginger, cloves, cinnamon, ground ivy, nutmeg, mace, honey, fennel, mint and a host of other additives were available to the Medieval brewer. They ranged from common to rare and expensive. Some imported ingredients were probably unknown in areas of the English countryside, but available in coastal cities.
Every age is arrogant, and we are no different. We assume that no one before ourselves knew how to do anything well. In fact, brewers throughout the Middle Ages produced excellent beer. During the high Middle Ages (1000-1400) English beer was widely exported and said to rival wine in clarity, color and strength. It was even presented to foreign kings as a prized gift.
Sparging did not even become feasible until the introduction of hops. We use sparging to extract the last bit of sugar because we want to emulate BudMilCoors. It is about economics, not necessarily about good beer. Try doing a Medieval style double mash (mash, draw off the liquid, mash again and draw of the liquid) and you will get two brews. One, a strong ale with OG around 1.075, and a small beer with OG in the mid to upper 1.030s.
It is likely that both would have been spiced by the Medieval brewer. The strong ale could be stored and the small beer was for everyday family use. Today we put hops in the small beer and call it English ordinary. We sparge so we can use minimal ingredients and get the same effect as our ancestors got from a second running of their mash.
Reproducing Medieval beers is both fascinating and rewarding. I particularly like my first running strong ale from pale and amber malts and spiced with ginger, toasted rosemary and fennel. I also treat the second running as Medieval brewers often did - I add honey to raise OG to over 1.070 and produce braggot. BTW, Wyeast No. 1728 (Scottish ale) works well with both. Yield is about 3 gallons each of two very different beverages from a single mash of 12 pounds of grain.
Let your imagination dictate the herbs, methods and uses for your Medieval beers. Our ancestors did.