"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": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "langcode": "en",
          "name": "Education",
          "orig": "en:Education",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "An INSET day."
      ],
      "id": "en-Baker_day-en-noun-4N0Z6Xip",
      "links": [
        [
          "education",
          "education"
        ],
        [
          "INSET day",
          "INSET day"
        ]
      ],
      "raw_glosses": [
        "(UK, education) An 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 eponyms",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Education"
      ],
      "glosses": [
        "An INSET day."
      ],
      "links": [
        [
          "education",
          "education"
        ],
        [
          "INSET day",
          "INSET day"
        ]
      ],
      "raw_glosses": [
        "(UK, education) An INSET day."
      ],
      "tags": [
        "UK"
      ],
      "topics": [
        "education"
      ]
    }
  ],
  "word": "Baker day"
}