Upvote:1
Timatic says the following regarding your situation:
National India (IN) /Residence United Kingdom (GB)
Embarkation United Kingdom (GB) /Destination Portugal (PT)
[Visa Information - Destination] Portugal (PT)
[Information For Normal Passports]
Passport required.
- Passports and other documents accepted for entry must be
valid for a minimum of 3 months beyond the period of
intended stay.
Visa required, except for Family members of a national of an
EEA Member State or Switzerland, with a residence permit
issued by United Kingdom to family members of a Union Citizen.
They are visa exempt for a maximum stay of 90 days.
[...]
Warning:
[...]
- Union Citizens are nationals of an EEA Member State and
Switzerland who moved from the country of nationality to
reside in another EEA Member State or in Switzerland.
The visa exemption for family members of a Union Citizen
applies if:
- they travel with or to join the Union Citizen, and
- the residence permit is issued by:
-- the country of residence, which must be different from
the country of nationality of the Union Citizen, or
-- the country of nationality of the Union Citizen, if the
Union Citizen and family member returned within 6 months
after departing from the country of residence.
So family members of Union Citizens don't require a visa, but you aren't one as you live in your country of nationality (the UK). Therefore, your wife would need a visa.
However, as @kiradotee points out, it should also be possible to get a visa on arrival:
Arriving at the border without an entry visa
It is always best for your non-EU family members to be well-informed in advance and have all the necessary documents before starting their journey.
However, if they arrive at the border with their passport but without an entry visa, the border authorities should give them the opportunity to prove by other means that they are family members of a mobile EU citizen. They can do so by providing proof of their identity and family ties with an EU citizen and, if travelling alone, proof that the EU citizen is already living in the host country. If they manage to prove it, they should be issued with an entry visa on the spot.
While an airline probably still wouldn't let you board (because they follow the Timatic rules), bus or ferry companies might not be as strict, so this might be a way to get to a Schengen country and then further to Portugal without having a visa in advance.