Home Office Reference - does it change?

[wildtiger]

My fiancee is currently completing an FLR(M). She applied before for a "MARRIAGE/CP" and was rejected, then applied again and was approved the second time. For her rejection she got a letter with a reference number (three letters + seven numbers) but for her approval she didn't get a letter - they just sent her passport without a letter.

My question is - will her current HO reference number be the same as the one on her earlier rejection letter or can it change (i.e. changed when she raised the second application for a fiancee visa)? Can she just enter this reference number for question 1.13 of the FLR(M)?

[CR001]

Likely it could have changed. Leave this question blank, it is not mandatory as it says 'HO reference if you have one'

[wildtiger]

Likely it could have changed. Leave this question blank, it is not mandatory as it says 'HO reference if you have one'

Thanks!