A quick PowerShell way to get the lats and longs of all stations in the Greater London area (and a bit more besides)

Get-StationsInLondon

$hashResult = @{}
if(!$TubeStationsRAW){
    $TubeStationsRAW =@()
    $page = 0
    while(1){
        $page += 1;
        Write-Verbose "Looking at page $page"
        $result = $(invoke-webrequest "https://api.tfl.gov.uk/StopPoint/Mode/tube,overground,national-rail?page=$page").content | ConvertFrom-Json
        if(!$result){
            return
        }
        $TubeStationsRAW += $result
        
    }
}
$TubeStationsMainEntrances = $TubeStationsRAW | ?{$_.stopType -eq "NaptanMetroStation"}  | select @{l="stationName";e={$_.commonname}}, lat, @{l="lng";e={$_.lon}}, @{l="type";e={"tube"}}, @{l="zone";e={($_.additionalProperties | ?{$_.key -eq "zone"}).value  -split '\+' -split '/'}}
 

if(!$TrainStationsRaw){
    $topLeft = @{
        lat = '52.1374073'
        lng = '-1.0101077';
    }
    $bottomRight = @{
        lat = '51.1173673'
        lng = '0.9008571'
    }
    $uri = "https://data.gov.uk/data/api/service/transport/naptan_railway_stations/extent?top-left-lat=$($topLeft.lat)&top-left-lon=$($topLeft.lng)&bottom-right-lat=$($bottomRight.lat)&bottom-right-lon=$($bottomRight.lng)"
    write-verbose $uri
    $TrainStationsRaw = $(Invoke-WebRequest $uri).content | ConvertFrom-Json
}
$TrainStations = $TrainStationsRaw.result | Select stationName, @{l="lat";e={$_.latlong.coordinates[1]}}, @{l="lng";e={$_.latlong.coordinates[0]}}, @{l="type";e={"train"}}

# Combine the results into one big array
$result = $TubeStationsMainEntrances + $TrainStations

# Create a results hash table with the station name as the key (this will deduplicate records with the same station name)
$result | %{
    $hashResult.($_.stationname) = @{
        lat = $_.lat
        lng = $_.lng
        type = $_.type
        zone = $_.zone
    }
}