Can it really be 50 years ...?

[Terry]

My arithmetic isn't very good, Terry.  I calculated upwards from 692kHz in 9kHz steps

Nothing wrong with your maths!

What you overlooked is that when the WARC 79 band plan was introduced, all channels became exact multiples of 9kHz so most* MW channels moved 1kHz higher.

Long Wave moved the other way, of course, so Droitwich on 200kHz  became 198kHz.

* To shoe-horn in an extra channel, pre WARC 79 some channels at the extreme HF end were reduced from the standard 9kHz width to 8kHz.