Anyone know of good source information for the colours of the Lancastrian lords, standards, and livery's?
Lance and Longbow Society publications. They have numerous publications. None are specifically Lancastrian; they cover all participants, possibly because so many changed sides. If you can be more specific in what you are looking for I might be able to point you in the right direction.
John
The original Osprey Men at Arms on the Wars of the Roses has some useful information about colours of livery jackets and badges. As John says, let us know which lords you are specifically interested in and I'm sure that from amongst us we can supply some pretty comprehensive information.
Flags and liveries for William Vaux, John Scudamore, Nicholas Latimer, Thomas Fitzhenry, Sir William Stock, Sir William Boteler.
In particular if any of the above had particular colours for their retinues.
At the time of the battle for Mortimer's Cross.
These are the liveries I have found so far.
I have found Owen Tudor in Dark Red/White.
Jasper Tudor in White/Green.
James Butler in Blue/Red.
I found this useful when working on my figs:
https://blog.vexillia.me.uk/2018/09/war-of-roses-livery-colours-database.html