A quick Google gave me these
/\b[a-z]{2}([1-9]|0[2-9]|6[0-9]|1[0-9])[a-z]{3}\b/i # current series
/\b[A-HJ-NP-Y]\d{1,3}[A-Z]{3}\b/ # previous series
/\b[A-Z]{3}\d{1,3}[A-HJ-NP-Y]\b/ # previous series
/\b(?:[A-Z]{1,2}\d{1,4}|[A-Z]{3}\d{1,3})\b/ # old series - letters first
/\b(?:\d{1,4}[A-Z]{1,2}|\d{1,3}[A-Z]{3})\b/ # old series - digits first
Looks like you'll have to test them individually.
