How did England’s bathing-water classifications change year to year?

What the comparison shows

The archive returned 458 in-scope site IDs and 4,254 classification records within 5,038 enumerated site/year slots.

Of 4,580 possible adjacent-year comparisons, 3,359 have valid ranked classes in both years; 1,221 are excluded.

The absence of a direct Excellent-to-Poor pair in the included observations does not establish that such a change is impossible, absent in excluded gaps or unlikely in future.

Good-to-Poor examples

These observed transitions prevent an overbroad inference that a previously good classification cannot worsen substantially. They describe annual labels, not overnight changes.

Annual transition coverage

The start year identifies its immediately following calendar year. No result bridges the missing classification year.

Which transitions occurred?

Rows are the earlier classification; columns are the following calendar year. Each cell is a count of valid pairs, not a probability.

Every valid adjacent-year comparison

Grouped by archive site ID, then chronological within each site. “better”, “worse” and “same” refer only to ranked classification labels.