Nearly all 'Mexican' restaurants in the UK are more properly described as Tex-Mex, or an American take on Mexican food. Los Locos is one of the better ones and it's a good night out but it's not truly Mexican.
Abut 20 years ago, there was a Mexican restaurant in Fulham Palace Road: the food was lovely. However, the British public didn't seem to like Mexican food and it went bust after about 18 months. I've been looking for another one ever since but haven't had much joy.