Excel, Numberplate Clarification - excel

Question

I am working on an excel document for fuel cards at the minute and my current issue is to write in a formula for validating number plates based on UK standard plates (two letters followed by two numbers then three letters i.e. BK08JWZ). At this point in time we are not considering personal plates in this just to keep things simple.
Ideally I need excel to look at the text in the box and confirm it to an agreed layout but I am struggling to find the right formula. The plates are in column 'I' and I have already added in another column after titled 'approved plates' in column 'J'but this can be deleted if it's not needed.
Results wise, I can do this one of two ways, to either get the excel document to highlight and number plates that do not match the DVLA standard , or have a column next to the number plate column that registers a boolean response to the recognition i.e. If it is valid (true) or if not (false).
Either way the plate needs to be able to be seen as it was currently, so if there is something wrong with it, it needs to be visible, not throw up an error message.
Any help would be very welcome.
All the information on UK standard number plates are on this site:
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/359317/INF104_160914.pdf

Answer 1

I would do it like this:
1) create a lookup sheet with data from the booklet. One column for allowed "memory tag" identiffiers (first two letters), one column for the allowed "age identiffiers" (first two numbers), and one column for allowed random letters (last three letters, full alphabet except I and Q)
2) strip spaces from the number plate for comparison
3) Use MID(numberplate,1,2), MID(numberplate,3,2) and MID(numberplate,5,3) to compare to each lookup list repectively (using INDEX()>0).
4) when all 3 parts are found in lookup lists the number plate is valid.

Answer 2

Try researching Regular Expressions or RegEx. This is a powerful programming tool to determine whether strings match specific patterns. You can use RegEx expressions to extract the pattern, replace the pattern or test for the pattern. Very efficient but not for the faint-hearted although there is plenty of help on-line. Try this article for starters.
The following RegEx may be what you need..
(?^[A-Z]{2}[0-9]{2}[A-Z]{3}$)|(?^[A-Z][0-9]{1,3}[A-Z]{3}$)|(?^[A-Z]{3}[0-9]{1,3}[A-Z]$)|(?^[0-9]{1,4}[A-Z]{1,2}$)|(?^[0-9]{1,3}[A-Z]{1,3}$)|(?^[A-Z]{1,2}[0-9]{1,4}$)|(?^[A-Z]{1,3}[0-9]{1,3}$)
This was copied from this article which gives a very full explanation using DVLA rules.
EDIT:
To use RegEx within Excel. In the IDE, Tools menu, select References and add the Microsoft VBScript Regular Expressions 5.5 reference.
With acknowlegement to user3616725s helpful observation.