Is it Holmegaard? Well, yes and no.
If I may quote from my website (because I've been wanting to do that for ages
Originally 'Gulvase' was only produced in an uncased dark olive green, amber and dark blue by Kastrup, and later Kastrup-Holmegaard. The vase is sometimes found in clear, light blue, grey smoke, and rauchtopaz (smokey-brown) colourways. They were made in quite large numbers by Cascade Glass of England under license from Holmegaard.
More information can be found here, as well as illustrations of every available colour produced by Holmegaard:Otto Brauer / Gulvase