Steve,
I can only presume that your Instructor felt that there would be no conflicting traffic (or jumpers) and wanted to get down quickly. I think that you did the right thing as caution is always best if you are not absolutely sure.
In small aerodrome left hand circuits I have seen people joining left base and straight in but never right base. Most of the time they would announce the fact and add 'giving way to circuit traffic'.
Personally I am sorry that this thread degenerated into a slanging match. Usually, amongst the flying community, there is great respect from both sides of the Atlantic.