Alpha Acid %
Beta Acid %
First Gold is a dwarf variety of hop meaning they could be grown on shorter trellis meaning less labour and maintenance (pesticide) costs. First Gold is another English variety developed in Wye College, released in 1995 it parents are Wye Golding and a dwarf variety. It shares similar characteristics to its parent Golding but has a higher alpha acid content.
As mentioned previously the First Gold hop shares similar character to Golding hops but have the added alpha acid levels which make it a great dual use hop. Like many English hops it has an earthiness but some of the more unique aroma qualities are the citrus and orange notes it can give a beer. The orange can come through as a marmalade character and this makes it perfect for lighter English Ales and bitters.
Many English hops share similar spicy, earthy qualities that are found in First Gold. Substituting with something like East Kent Goldings is ok but for aroma purposes you will be missing the citrus, orange note that First Gold has. Challenger can have a marmalade character so take a look at these.
A nice single hop bitter from the Badger Brewery is a available called First Gold http://www.hall-woodhouse.co.uk/beers/badgerales/cask_firstgold.asp (funnily enough) and it portrays the hop well.
Salopian Breweries Golden Thread is hopped three times with First Gold and produces some of the spicy, citrus notes the hop has http://www.salopianbrewery.co.uk/beers.php