I'm lucky enough to be the custodian of a historic property with a small walled garden which I am also responsible for. I have a pair of standard roses which are so old that they have trunks rather than stems!
Whilst I'm normally fearless at pruning these two are a real faeture in the garden. One is now bigger than the other as it was damaged by snow last winter.
You'll need to prune your roses to make sure that they grow healthily this summer. A standard rose is pruned in the same way as a bush rose except that you need to ignore the main stem. The shoots that come out of this are the same as shoots emerging from the ground in a bush rose. Be sure to use sharp secateurs/saw and disinfect your implements regularly. Cut to a bud that faces in the direction you want the stem to grow. Outward buds are good as this opens out the plant and promotes airflow. Cut out dieback until you reach healthy tissue. Be sure to remove very thin stems, and stems that rub against each other. Finally, if you want some more encouragement, have a look at Adam's blog on this subject.
Thanks, Emma. I'm feeling a bit chicken about this. They are the first thing visitors to the garden see, flanking a weathered brick path. Whilst they have been trimmed to keep them roughly in shape, without leaves it's evident that they haven't had a "proper" prune for some time.