Tell me about that Whitworth. I owned 5 60's era Triumphs: 1 Spitfire and 2 Tr-4's and 1 Tr-4A. Then there was the Tr-4 that I drove home and parked in the garage repertory to restoring. Then I retired from the Air Force and bought a business. That was the last of the restoration effort.I hate when a plane hardware has been hacked.
The original screw may have been lost. In my restorations I have had a few planes with bad hardware especially the tote and knob screws.
This is the best summary of the thread sizes and specifications I have found so far. Record followed the Stanley standards.
The original tote screw was 7/32nd in dia x 20 tpi Whitworth thread. As a Brit I grew up learning to hate Whitworth threads, popular on British cars up to the 60's.
Good luck finding a tap if you want to go back to original. I saw one on EBay but crazy price.
If you weld the hole you can resort to a #12 screw, the closest size to the original.
I would not go bigger than 1/4in dia since the hole size could weaken the tote, especially in a heavy plane like a No. 7.
It sat there for 16 years until I sold it in pieces.