I have a flight in September from Thailand to the UK with a layover in India. The layover is just under 14 hours, I am a UK citizen and I do not plan on leaving the airport. I haven't been able to find any firm advice on whether I will need a transit visa. The UKGOV.com official site says a transit visa will be required to travel through India, as I am travelling by air into India and straight back out again, will I need a visa?
One possible duplicate has not (yet?) been answered and the other focuses on French citizenship and contains some information that seems inaccurate.
All the 'Indian' sites I have seen are of terrible quality and very confusing so I suggest relying on the unequivocal:
To transit through India you will need a transit visa.
with support from World Travel Guide:
For UK nationals: transit visa: £56
valid for three days of transit through India within 15 days of the date of issue.
At least at the moment you are not eligible for a visa-on-arrival arrangement.