What is the "other type of visa" needed travelling from India to Dublin via Heathrow?

Question

I am an Indian Citizen and have Irish Visitor visa and will be travel transiting through London Heathrow to Dublin. The stop over is 3 h 45 mins.

As I am transiting to common travel area (Ireland), it states on the website that I may need another type of visitor visa.

Statement from uk gov website 3. Visitor in Transit visa:

"You’ll need to apply for another type of visitor visa if you’ll be either: travelling to the Republic of Ireland, the Channel Islands or the Isle of Man"

What type of visa is that?

Answer 1

Your question is what is meant by: "You’ll need to apply for another type of visitor visa if you’ll be either: travelling to the Republic of Ireland, the Channel Islands or the Isle of Man".

In the context of transit visas, it means that the UK will not process a transit visa application if your destination is within the Common Travel Area (CTA). Instead, you will need a visitor visa issued by the An Garda Síochána (or alternatively one of the Bailiwicks or the IOM Government).

Based upon what you wrote, you have one of these so do not require a UK Visitor in Transit Visa.

NOTE: if you found the language on the gov.uk site ambiguous or otherwise unclear, you can tell them about it at https://www.gov.uk/contact/govuk They are grateful to know about those things.