"Baker day" meaning in English

{
  "etymology_text": "After Kenneth Baker, the minister who introduced them in 1988 as part of a series of education reforms.",
  "forms": [
    {
      "form": "Baker days",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Baker day (plural Baker days)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "British English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with language name categories using raw markup",
          "parents": [
            "Entries with language name categories using raw markup",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English terms with non-redundant non-automated sortkeys",
          "parents": [
            "Terms with non-redundant non-automated sortkeys",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Education",
          "orig": "en:Education",
          "parents": [
            "Society",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "INSET day"
      ],
      "id": "en-Baker_day-en-noun-WYCDYpkK",
      "links": [
        [
          "education",
          "education"
        ],
        [
          "INSET day",
          "INSET day"
        ]
      ],
      "raw_glosses": [
        "(UK, education) INSET day"
      ],
      "tags": [
        "UK"
      ],
      "topics": [
        "education"
      ]
    }
  ],
  "word": "Baker day"
}

{
  "etymology_text": "After Kenneth Baker, the minister who introduced them in 1988 as part of a series of education reforms.",
  "forms": [
    {
      "form": "Baker days",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Baker day (plural Baker days)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "British English",
        "English countable nouns",
        "English entries with incorrect language header",
        "English entries with language name categories using raw markup",
        "English eponyms",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with non-redundant non-automated sortkeys",
        "en:Education"
      ],
      "glosses": [
        "INSET day"
      ],
      "links": [
        [
          "education",
          "education"
        ],
        [
          "INSET day",
          "INSET day"
        ]
      ],
      "raw_glosses": [
        "(UK, education) INSET day"
      ],
      "tags": [
        "UK"
      ],
      "topics": [
        "education"
      ]
    }
  ],
  "word": "Baker day"
}