there is no mention of a flax mill in Bawden et al 'Industrial Archaeology' but they comment that quite likely confused in reports with tuck mills (similar in non-corn) - think there was a tuck mill in Glen Wyllin.
The name Sampson might be Dublin based - a Murray (cousin of Bishop Wilson) married a Dublin Sampson and her daughters married into several well known familiies inc Curgheys (her will is on Island but I've not transcribed it)