Standard roses.

Bush roses would have been a better choice to grow as standards. I'd have thought David Austin roses are a bit too big to grow as standards as they tend to grow naturally as tall shrubs. However, as you've already got them, I'd prune them fairly hard in late winter, by cutting each main stem back by at least half to an outward facing eye, and removing all inward growing and any weak or spindly stems. You want to aim for 4 or 6 stems of at least pencil thickness growing outwards with side shoots growing outwards from these.

Although you can do that with bush roses whether you can train Daivid Austin roses to behave in a similar way I'm not sure.