Lancastrian supporters took advantage of Edward's imprisonment to stage uprisings.
From the en.wikipedia.org
Lancastrian delight can only have been increased by Yorkshire's continuing travails.
From the independent.co.uk
Lancastrian specialities are made with farm produce in the on-site kitchen.
From the independent.co.uk
As a lancastrian I know this is something that could be spread and celebrated elsewhere.
From the guardian.co.uk
Lancastrian strength ranges from 10,000 to 30,000 men, with 7,000 to 15,000 on the Yorkist side.
From the en.wikipedia.org
Lancastrian Laura Barton and her Yorkshire friend, Alice Wignall, agree on most things, except which county is best.
From the guardian.co.uk
More examples
A member (or supporter) of the house of Lancaster
Of or relating to the former English royal house or their supporters; "Lancastrian royalty"
Of or relating to the English city of Lancaster or its residents; "Lancastrian city center"
(Lancastria) *Lancashire, a British county and former duchy. * The English House of Lancaster and its supporters ("Lancastrians") *RMS Lancastria, British navy ship sunk in 1940 with the loss of 4000 lives. * another name for the tribolite Changaspis