This is probably, as Pamela has suggested, Jobling. This appears to be a variant of the 11600 'Open Footed Vase'. It is possible that the design was altered during production as was the case with the ballerina figure, however, I have yet to see any evidence to support this.
Here's a pic of the other version with the genuinely open foot
http://glassgallery.yobunny.org.uk/displayimage.php?pos=-6022 (this is definitely Jobling as it's marked with the reg. no. on one of the legs).
Regarding colours, Jobling made at least two shades which could be described as amber, a pale yellow and a much deeper brown
http://glassgallery.yobunny.org.uk/displayimage.php?pos=-6115 &
http://glassgallery.yobunny.org.uk/displayimage.php?pos=-5952 , however, neither seem to match the colour of Ken's vase, so I am beginning to have some doubts.
I have Pamela's old example of this pattern (
http://www.pressglas-pavillon.de/vasen/08008.jpg) here on my shelf., the colour of this one is consistent with Jobling's lighter amber colour.
Another observation is that the open and closed version of this vase do differ greatly. It is not simply a case of the legs having been closed in, the moulds show many differences. The closed versions has much slimmer legs, a rounded foot with a base star, rather than a panelled foot which is plain underneath on the open version. The leaves and flowers are also completely different, the leaves are much slimmer and more pointed on the closed version.