I can't answer that but only tell you what I have heard or read.
A true Triumph dealer can get you new keys using your vehicle id number. If you have the key code, they should be able to cut it for you. Otherwise, the keys will have to come from the UK. If the dealership is an add on to an existing bike dealership, they might say no.
Getting a locksmith to decode your ignition lock might be pricey unless you know someone. I have seen people saying a key blank for a Kawasaki will fit our ignition. It is a KA33. Another maybe is the ILCO blank X278.
The above info might be fairy tales. All you can do is see how far you get with this.
If you go to a Triumph dealer, ask them if they also have a complete ignition with keys in stock. <insert big laughs here>
If I were in this situation, I would just order a complete new ignition from World of Triumph after getting a 'no' from my dealer.
some locksmiths have the key blanks in ILCO brand. for 08 bonne the ign key #x278 and ka33 works, a little long but can be shortened, it dosen't have to be. for the steering lock use ILCO #PZ2, look at your lock key and you'l see the top stright edge has a slight bevel on one side, this is easy to copy on the new blank with a file.