Historically, due to different dyes, the blue colour varied from sky blue to navy blue. Due to more weather resistant dyes, the dark blue was chosen for the Union Jack and also sometimes used for the Scottish flag. Likeky for historical reasons, “back to the roots”, in 2003, the Scottish parliament specified a lighter blue tone than the one used for the Union Jack.
Historically, due to different dyes, the blue colour varied from sky blue to navy blue. Due to more weather resistant dyes, the dark blue was chosen for the Union Jack and also sometimes used for the Scottish flag. Likeky for historical reasons, “back to the roots”, in 2003, the Scottish parliament specified a lighter blue tone than the one used for the Union Jack.
https://en.wikipedia.org/wiki/Flag_of_Scotland#Design