Take a look at the screen grab of the factsheet below and there is the following: "UK tide gauge records show substantial year-to-year changes in coastal water levels (typically several centimetres). We recommend that coastal decision makers account for this variability in risk assessments, particularly for shorter-term planning horizons."
You can enlarge the above screen grab for easier reading, or go to the link. I have written to the Met Office to ask if they believe this to be correct and am waiting for a response.
Below is the record for Portsmouth, and while it is true to say that there is year to year variability of several centimetres, this is both up and down and, when it is averaged out, the actual rise is much lower (only around 2mm). So what point are they trying to make? Could it be to give the impression that sea level is rising by "several centimetres" a year?