Anyhow, yes they can, it's perfectly normal practice for the landlord to have a key, they are not allowed access without notifying you in advance though.
hi, I have previously remted 3 properties and in each the landlord had a key. This made sense to me as in the first one, we had a gas leak while we were both at work and the ll was able to sort it out and in the second one when our pipes burst we were able to phone him and not have to wait in for him to come and sort them out