Very interesting thread and many of the comments are extremely pertinent, however I am just astonished that anyone would install that CU in that location. No matter what technical justification might be relevant, it's just a bad installation idea.
A few years ago I was doing some work on a new-build housing estate where all the houses had the CU installed at high level in the downstairs cloakroom. This was a mainstream builder and I am aware the same installation was carried out on other estates. Now, I accept the cloakroom had no bath or shower, but the only way to gain access to the CUs in these houses was by standing on the WC...there's no room to place a ladder or hop-up. I accept these houses passed BC regulations, but in my opinion the CU should not be mounted high up above a WC. A less-able person would find access extremely tricky and indeed hazardous, and for that reason alone it shouldn't be allowed.