Simple working Example of json.net in VB.net

Your class JSON_result does not match your JSON string. Note how the object JSON_result is going to represent is wrapped in another property named "Venue".

So either create a class for that, e.g.:

Public Class Container
    Public Venue As JSON_result
End Class

Public Class JSON_result
    Public ID As Integer
    Public Name As String
    Public NameWithTown As String
    Public NameWithDestination As String
    Public ListingType As String
End Class

Dim obj = JsonConvert.DeserializeObject(Of Container)(...your_json...)

or change your JSON string to

{
    "ID": 3145,
    "Name": "Big Venue, Clapton",
    "NameWithTown": "Big Venue, Clapton, London",
    "NameWithDestination": "Big Venue, Clapton, London",
    "ListingType": "A",
    "Address": {
        "Address1": "Clapton Raod",
        "Address2": "",
        "Town": "Clapton",
        "County": "Greater London",
        "Postcode": "PO1 1ST",
        "Country": "United Kingdom",
        "Region": "Europe"
    },
    "ResponseStatus": {
        "ErrorCode": "200",
        "Message": "OK"
    }
}

or use e.g. a ContractResolver to parse the JSON string.

Imports Newtonsoft.Json.Linq

Dim json As JObject = JObject.Parse(Me.TextBox1.Text)
MsgBox(json.SelectToken("Venue").SelectToken("ID"))