using System.Text.RegularExpressions;
public static void Main()
XDocument X = XDocument.Load("https://weather-broker-cdn.api.bbci.co.uk/en/observation/rss/2647553");
var test = X.XPathSelectElement("//item/title").Value;
Console.WriteLine(Regex.Match(test, @"GMT: (.+?),").Groups[1].Value);
var weather = X.Element("rss").Element("channel").Element("item").Element("title").Value;
Console.WriteLine(Regex.Match(weather, @"GMT: (.+?),").Groups[1].Value);