It is easy to put a border around this flag image :
	[[File:Ensign of the Air Training Corps.svg|border|96x176px]]

Summary

DescriptionEnsign of the Air Training Corps.svg	English: An improvement of ATC Ensign.svg by Sakurambo at English Wikipedia: grab Union canton from Image:Government Ensign of the United Kingdom.svg, correct colors, slight position change for the badge, bigger size to allow big PNG for end-users, fuller name.
Date	17 May 2007
Source	This vector image includes elements that have been taken or adapted from this file:  Flag of the United Kingdom.svg.
Author	Sakurambo

Original summary at Wikipedia

Ensign of the w:Air Training Corps

Own work, based on w:Image:Atcensign.JPG and w:Image:Air Training Corps crest.svg

The design of this ensign dates back more than 60 years and is thus in the public domain.

Original file history at Wikipedia

11:34, 17 May 2007 . . Sakurambo . . 951×474 (61,783 bytes) (Own work, based on Image:Atcensign.JPG and Image:Air Training Corps crest.svg The design of this ensign dates back more than 60 years and is thus in the public domain.)

Licensing

Original licensing from English Wikipedia:

Sakurambo at the English-language Wikipedia, the copyright holder of this work, hereby publishes it under the following license:

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.http://www.gnu.org/copyleft/fdl.htmlGFDLGNU Free Documentation Licensetruetrue

	This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
	Attribution: Sakurambo
	You are free: to share – to copy, distribute and transmit the work to remix – to adapt the work Under the following conditions: attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
	This licensing tag was added to this file as part of the GFDL licensing update.http://creativecommons.org/licenses/by-sa/3.0/CC BY-SA 3.0Creative Commons Attribution-Share Alike 3.0truetrue

This file is licensed under the Creative Commons Attribution-Share Alike 2.5 Generic, 2.0 Generic and 1.0 Generic license.

You are free:

• to share – to copy, distribute and transmit the work
• to remix – to adapt the work

Under the following conditions:

• attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
• share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.

https://creativecommons.org/licenses/by-sa/2.5CC BY-SA 2.5 Creative Commons Attribution-Share Alike 2.5 truetrue