At 12 noon GMT, the time in Madrid is 1 PM during Central European Time (CET), which is typically observed from the last Sunday in October to the last Sunday in March. However, during Central European Summer Time (CEST), which runs from the last Sunday in March to the last Sunday in October, the time in Madrid would be 2 PM. Therefore, the time in Madrid at 12 noon GMT depends on the time of year.
12 noon
17:00 GMT is 11:00 AM Central Standard Time (CST) or 12 Noon Central Daylight Time (CDT).
1700 GMT is 11:00 AM Central Time. Central Time is 6 hours behind GMT, so you would subtract 6 hours from 17:00 GMT to get the local time in Central Time.
When it's 12 noon NDT on Newfoundland Island, it's 2:30 PM GMT. When it's 12 noon NST on Newfoundland Island, it's 3:30 PM GMT.
From the last Sunday of March until the last Sunday of October, London is one hour ahead of Reykjavík. During the rest of the year there is no time difference between London and Reykjavík. When it's 12 noon GMT in Reykjavík it's either 12 noon GMT or 1 PM BST in London.
Greenwich Mean Time (GMT) is the time at the Prime Meridian, which is 0 degrees longitude. Tokyo, located at 140 degrees east, is 9 hours ahead of GMT. Therefore, when it is 12 noon on Monday at Greenwich, it would be 9:00 PM on Monday in Tokyo.
As I write this it is 8:05 PM there. For reference: The Dominican Republic time is GMT -4; Both Cuba & Florida in the USA are GMT-5; Brazil is GMT -3; and England itself is GMT. So... At 3 PM London time it is: 12 noon in Brazil; 11 AM in the Dominican Republic; 10 AM in Cuba
CST is UTC-5, which means it is five hours behind GMT/UTC. Therefore, 5pm in GMT is 12 noon in CST.
When it's 12 noon EST in Jamaica, it's 5 PM GMT in Ghana.
Greenwich Mean Time (GMT) is the time at the Prime Meridian (0 degrees longitude). Each degree of longitude corresponds to a time difference of 4 minutes. At 20 degrees east longitude, the time would be 20 degrees × 4 minutes = 80 minutes ahead of GMT. Therefore, if it is 12 noon at Greenwich, the time at 20 degrees longitude would be 1:20 PM.
At 1700 GMT, it is 12:00 PM (noon) in Tulsa, Oklahoma, which is in the Central Time Zone (CST or CDT, depending on the time of year). During Standard Time (November to March), Tulsa is 6 hours behind GMT, and during Daylight Saving Time (March to November), it is 5 hours behind. Therefore, at 1700 GMT, Tulsa is on Central Daylight Time.
There is not enough information to answer this question, unless by 'mid-day' you mean exactly 12 noon, Fiji time.