A little-seen plaque about codebreakers hides its own code.
Walk to the end of the beer wine garden behind Gordon's, head up some steps, and you'll spot this curious green plaque.
The memorial, at 13-15 York Buildings, marks the first home of GCHQ, the intelligence service concerned with signals and codebreaking. The agency is considered so important that Queen Elizabeth II herself unveiled the plaque, to mark GCHQ's centenary in 2019.
The keen eye will spot that this is no simple plaque. Certain letters and numbers are undermarked with dots and lines. It's not too hard to decipher, so we won't print the solution here, but it can be found easily elsewhere online.
GCHQ has grown a bit over the years. From a dozen or so people tucked away off the Strand in its earliest days, it now occupies 'the Doughnut' near Cheltenham, and employs over 7,000 people.
By the looks of it, parking is also a little easier in the current home.
With thanks to London Remembers for the tip-off.
