I will try to find out how guide dogs are trained to do this. I've been using the 'Wait' command at each step as we go down, then commanding Uly to go down further by saying 'One step', again repeating the 'Wait' command whenever he appears to be going too far. I also, incidentally, keep one hand firmly on the handrail (where there is one available), in this way I am braced if he does go down too fast. Best of all though, is that 'Wait' command, now he really knows it, and the tone of voice that goes with it (sharp, commanding action), it pretty much stops him in his tracks (exactly as intended).
This will really come into its own when I have to take Uly down very steep stairs (such as on a boat), Being able to hold him (with my voice) on the steps as we go down could save a lot of grief.
We did take Uly on the car ferry across to the Isle of Wight last Easter, and we had to go up and down a number of flights of stairs. We sort of managed them, but next time will be much, much better I'm sure.
For readers unfamiliar with the UK, Isle of Wight is a small isle (10 miles x 15 miles approx) off the south coast of England. It is know for being a good place to find fossils, it was also a home of Queen Victoria who lived at Osborne House. A lot of sailing goes on around the Isle and of course hosts Cowes Week Regatta. We go to the Isle of Wight because it has a somewhat unspoiled, slightly old-fashioned feel about. It has some lovely beaches & coves, walks and country pubs.