What date did his wife get her citizenship on?
While the British authorities would not be bothered about it, Indian law would punish her for using the Indian passport to travel more than 90 days after the citizenship ceremony (N.B.- after the citizenship ceremony, not after getting a British passport). If she were not to surrender the Indian passport within 90 days, there would be additional fines charged when doing so and there MAY be issues with getting a future Indian visitor visa or PIO/OCI.
Also, when she is travelling back, she would need to prove her right to abode in the UK. She may want to carry her naturalisation/registration certificate with her. Somebody on another thread mentioned that the Home Office deletes your biometric data off their system when you become a citizen and hence, while the BPR ILR card remains valid, the data on it can not be verified.
http://www.immigrationboards.com/britis ... l#p1055507
I just returned to the UK two days ago through Heathrow. When they used my BRP and asked for my fingerprint scan, nothing came up. Apparently things have changed, and they are not allowed to store British citizens fingerprints in the system anymore. Since I wasn't traveling with my naturalization certificate, I had to stand around and wait until they verified my citizenship. It only took a few minutes, but it did extend things a bit when entering the country.
So, I wouldn't recommend anyone traveling with their BRP after getting citizenship. The woman at immigration asked me if I had my certificate with me, and I said I didn't, as they didn't tell me when I received it that I would need it for travel. My suggestion is to definitely take your certificate with you as they will eventually delete your fingerprints from the system which basically invalidates your BRP for entering the country.
Hope this helps.
