915 d4

I'm not particularly familiar with the UK but I'm sure you could find one on eBay. Cheers

Since the 917 models are out, you'll need to see if there is D4 inventory left for special orders. The PGA Titleist players have moved to the 917 D2/D3 at this point. Might be worth checking those out. Your local club that handles Titleist should be able to check on the ordering through the UK office. The D4 was a Made to Order, so there won't be much chance to find a new one retail.