That's about as close a commission number to mine as I have seen. I have TS64566L with EB62851. It is interesting that they vary by about 2000 from the commission number, but mine is 2000 less and yours is 2000 more!
According to Bill Piggott's Orginal TR book the EB number was attached by Standard Triumph once the car was painted and trimmed, which is why it is close to the commission number. The other brass plate below the EB number shows the Mulliner number. I have heard that the Mulliner number should be painted, but the EB number should remain unpainted brass.