Xperia M4 Aqua (E2303) - Root with LOCKED BOOTLOADER (Bootloader unlock allowed: No)

Sony Xperia M4 Aqua (E2303) Root Guide
For devices with LOCKED BOOTLOADER (Bootloader unlock allowed: No)

I searched for days, weeks and months to find a way to root my Xperia M4 Aqua E2303 phone without any luck at all.
The problem is that every guide I could find means having to first unlock your bootloader before being able to root.

Dialling *#*#7378423#*#* will give you the 'Service Info' menu, and tapping 'Configuration' will give you more information.
Under 'Rooting Status' you will see Bootloader unlock allowed: No. If this is not the case, then I don't know if this guide will help you. However, if this IS the case, then the below allowed me to root my device.

My device info:
Android Version: 5.0 Lollipop
Kernel Version: 3.10.49
Build Number: 26.1.A.3.111

Disclaimer: I will not accept any responsibility for your device. You are using this guide and any linked files AT YOUR OWN RISK. Due to Bootloader being locked, this guide doesn't include flashing the recovery! I am sharing this in the hope that it will help someone having the same problems I did.

So, here we go.
1) Dial *#*#7378423#*#* then tap 'Configuration' then look under 'Rooting Status'. If it says 'Bootloader unlock allowed: No' then go to step 2.
2) Download the kit at http://s000.tinyupload.com/?file_id=...10233527948260
3) Unzip the kit. Make sure you have installed your Xperia M4's drivers including fastboot and ADB. These are also included in the kit you have just downloaded if you do not already have them.
4) Turn on your phone. Go to 'Settings' then go to 'About Phone'. Keep tapping on 'Build number' and you will unlock developer options.
5) Go to 'Settings' then go to 'Developer Options'. Tick 'Enable OEM unlock' and 'USB debugging'. Also UNTICK 'Verify apps over USB'.
6) Make sure your phone is well charged, and plug in your phone via USB cable. A message will appear asking if you give your PC debugging permission. Tick 'Always choose this option' and then tap 'Allow'.
7) On your computer, go to the kit you unzipped in Step 3 and go to the rootkitXperia_E23xx_26.1.X.3.xxx folder.
8) Double click on 'Install.bat' and an automated Command Prompt will open up (looks like DOS)
9) The bat file will send all the required files and scripts to your phone. When complete, your phone will restart.
10) When your phone has restarted, the Command Prompt will say 'Press any key to continue'. Push any key and the Command Prompt will close. If not, I am told the Rootkit can be run again until it works - however it worked first time for me.

If all has gone well, your phone will now be rooted and will have the SuperSU app installed. Download 'Root Checker Basic' from the app store to verify your root status.

The Rootkit files used were found at a similar thread here (http://forum.xda-developers.com/m4-a...bolek-t3340399). This post/guide aims to be a more in-depth and approachable method for those not so comfortable working it out for themselves.