This IS a scam the "Accident compensation Commission" just received a call from them and I work in insurance do I had heard about them be for the guy said his name was Mark. I asked what government departments they were associated with and they hung up. Suprise suprise.

Do not answer the phone if this number rings and do not call them back.
We get 3-4 calls from them in a day and they are a serious pain.

Hung up once I answered

These people use multiple numbers, always the same scam story, someone who uses your phone has been in an accident and it's a compensation claim. If you try to call the number back it either rings out or it's already disconnected. If you swear at them they hang up quickly.

Have had multiple hang-up calls from this number (to our office number) recently. Had our telco block it.

didn't leave a voicemail

Just had a call by a man with an accent from the " accident compensation department" asking if anybody had an accident in the last 12 months - I relied "No " and he hung up.