You can find a great introduction to ECW flags here:
This gives the full introduction from The English Emblem Tradition Vol. 3: Emblematic Flag Devices of the English Civil Wars 1642-1660 by Alan R. Young, 1995. I own this book and it is great, giving a description and illustration (when known) of every known flag from the English Civil Wars that bears an emblem and slogan of some sort. This does mean however that most of the flags included are cavalry cornets. The book doesn’t include the more generic foot ensigns.
1. Ensigns
Ensigns were carried by each company of foot. They were usually about 2 metres square, so in 1/72 scale should measure about 2.8cm square. They were carried on short poles (around 2.3 metres long) to allow flourishing and twirling. In both Parliamentarian and Royalist armies the ensigns followed a similar design scheme. The ensign belonging to the Colonel was usually plain, the Lieutenant-Colonel’s ensign bore only the cross of St George in the top left corner. The ensigns of the Captains commanding each of the (usually 5) companies usually bore a number of heraldic devices or symbols, the number of which showed the seniority of the Captain. The more senior the Captain, the fewer devices.
This scheme is well illustrated on some free flags for the Earl of Essex’s army available on the Warflag site:
http://www.warflag.com/flags/ecw/ecw.shtml
Some other free ensigns are available here:
http://tmg110.tripod.com/british6.htm
http://www.quindia.com/studioart08.htm
Covenanter, Scots Royalist and Irish Confederate ensigns were a little different. Covenanter ensigns were usually, but by no means always, based on the St Andrew’s saltire, with some variation on the motto ‘Covenant for Religion, Crown and Kingdom’ or similar. In addition, the ensigns often included some heraldic emblem, often denoting the regiment’s colonel.
A few beautiful flags for Scots Royalists, Covenanters and Irish are available on the Project Auldearn blog:
http://auldearn1645.blogspot.com/search?updated-max=2008-08-01T14%3A29%3A00-07%3A00&max-results=7
If you want to buy ensigns for your ECW armies, the only option I am aware of in 1/72 scale is Rofur Flags:
http://www.rofur-flags.de/liste2a/liste2a-engl.htm
Some are also available from Tiny Tin Troops, but I couldn’t work out what scale these are:
http://www.tinytintroops.co.uk/Flags/flags_ECW.htm
2. Cornets
Cornets were much smaller than ensigns, measuring only 60cm square, which is about 0.8cm in 1/72 scale! I usually make them a lot bigger than this, going for the visual appeal over strict accuracy. Cornets were carried on lances between 2.44 metres and 2.74 metres in length. Unlike ensigns, cornets usually had a fringe, and bore a much greater variety of images and slogans. Many included outright propaganda messages. I’m not aware of any free cornets on the internet, or of anyone selling them in 1/72 scale. So I’ve decided to make some, and will put them up on this blog as they become available. Just resize them as you see fit on a colour printer. If anyone uses these I would love to see the finished product. Here are two for starters:
Parliamentarian Cornet belonging to Captain Dobbins of Worcestershire (1642-). Motto means 'While I breathe, I hope.'
Pariamentarian Cornet (1642-). Bearer unknown. Motto means 'Death for me is gain.
3. Guidons
Guidons were carried by dragoons. They were a similar size to cornets, but were distinguished by having a swallow-tail shape. The designs followed a similar scheme to infantry ensigns.