The pictures help. I am now reasonably certain you have an Enfield Mk VI revolver, as opposed to a Webley Mk VI. There should be an Enfield crest on the right side of the frame. You can verify that since there are no photos of the right side of the frame. All the info below is simply "to the best of my knowledge". I welcome any corrections.
Backstrap markings are typically unit/date/rack markings. Ian Skennerton is THE British firearms expert. In his book "The Broad Arrow" he indicates that firearms marked K.A. were assigned to the Karachi Artillery Volunteers unit and, as you surmise, 4.41 is the issue date of April, 1941 (not the manufacture date, which is in the 1920's). Pakistan did not split away from India until 1947 so although Karachi is in modern-day Pakistan, it was a part of India in 1941, and India was a major British empire ally. Had there been a third line on the backstrap of your revolver it would typically have been a rack or issue number.
Also, by 1941 all the No. 1 .455 revolvers would have been relegated to second line status. The (then) new Enfield No. 2 revolvers in .38/200 caliber would have been the first line issue service sidearms, which is yet another reason why transference of your revolver to India is logical.
Speaking of the broad arrow, it is a British military acceptance mark and British military firearms usually have bunches of them. You can see a good example on the left side of your trigger. Looks like sorta like this... ->. When a British firearm was considered obsolete it was often "Sold Out Of Service", the symbol for which is two broad arrows facing each other like this... -><-. Looks more like an asterisk but is supposed to be two broad arrows. I think I see this mark on the left side of the top strap but when I try to zoom in the photo gets too fuzzy to be positive. However, in conjunction with the two broad arrows one sometimes sees the "England" stamp as well, especially if it was going to the U.S., so I think it probably was sold out of service.
When the letter "N" is stamped on a British firearm it usually stands for Navy. The letter N on your revolver is a bit smaller than what I am accustomed to seeing on Webley Mk Vi's, and one probably only sees maybe one Enfield Mk Vi for every 10 Webley Mk VI's so I can't be positive of the naval connection, but it's my best guess. If I am correct I would expect that this marking would have been applied in its earlier life prior to the Indian transfer.
I'm not at all certain about the star but it has been customary for years to mark British rearsenaled/refurbished firearms with a F.T.R. mark, standing for Factory Thorough Repair, so if it had been refinished and reissued it would probably have had worn small parts replaced at the same time and would normally be sporting the FTR marking. One internet source says a 5-pointed star on the butt of a handgun indicates "Aid From England", i.e. that it was a gift to a foreign ally. This would make sense since your revolver was transferred from England to India but again, I'm not sure that the source is correct. Just don't know for sure.
Did you try the nickel test to see if it is in its original .455 caliber? This is a big deal with respect to the value of the gun. Unconverted .455 revolvers are worth considerably more to collectors than those that have been converted to .45 acp.