Go Outdoors are selling a Lowe Alpine Polar Down jacket. The RRP is £100, with £69 as the next cheapest price.
They have a choice of two colours and a range of sizes. You might be able to pick one up in store for £34.99.
Its not the greatest specification as down jackets go: Its 80% goose down. 20% synthetic down, with 600 fill power (700 would be better). It weighs 510g.
Down jackets are awful if you get them wet. However, when they are kept dry, they are fantastically warm, soft and light weight. You can also squish them down into a very small space if necessary.