How interesting! I never knew the police had a data API we could use! I would suggest using Google Apps Script, you can easily import the JSON data using that.
For example to first fetch the data you can use the URL Fetch Service like so:
var data = UrlFetchApp.fetch("http://data.police.uk/api/crimes-street/all-crime?lat=52.629729&lng=-1.131592&date=2013-01");
This will return the raw JSON data for you to play with how you see fit.
You can then iterate over the objects, adding them to an array to add to the spreadsheet. A complete function might look something like the below. I know it's extremely messy. Now I know this police API exists I plan (when I get some free time) to set up something similar, I'll update this answer when I have a better solution but I have tested the below and it does write all the data from a URL to the spreadsheet.
function importPoliceData() {
var data = UrlFetchApp.fetch("http://data.police.uk/api/crimes-street/all-crime?lat=52.629729&lng=-1.131592&date=2013-01");
var jsonData = JSON.parse(data.getContentText());
var dataArray = [];
for(var i = 0; i < jsonData.length; i++){
var thisRow = [];
for(var a in jsonData[i]){
if(typeof jsonData[i][a] == 'object'){
for(var o in jsonData[i][a]){
if(typeof jsonData[i][a][o] == 'object'){
for( var p in jsonData[i][a][o]){
thisRow.push(jsonData[i][a][o][p]);
}
} else {
thisRow.push(jsonData[i][a][o]);
}
}
} else {
thisRow.push(jsonData[i][a]);
}
}
while(thisRow.length != 13){
thisRow.push("");
}
dataArray.push(thisRow);
}
var sheet = SpreadsheetApp.getActiveSheet();
var range = sheet.getRange(1,1,dataArray.length, dataArray[0].length);
range.setValues(dataArray);
}