@roxie this is a Rails position but if you’ve done backend work before you can probably pick up the basics of Rails in pretty short order. in my experience these kinds of jobs in the US are not very competitive and i wouldn’t be surprised if the same were true in the UK.
as a word of warning if you do get the position, Hyrax can be a pretty steep learning curve, but as an upshot i doubt anyone applying will have much existing experience. it will position you well to pick up similar jobs in the future.