Remove all characters up to a specific character

Searched to no avail... I want to remove all characters in TITLE up to a specific character, leaving everything after it.

For example: "blah blah x This is the good part"

I want to remove everything up to "x". Bonus if it can also remove the space after it. Conditions: It will be the first instance of that character. But not the first space.

Could you give a real example?
For the dummy text I suggest:
$regexp('blah blah x This is the good part',.*\s.\s(\u.*),$1)

I'll have to see if I can remember it. I fixed them all manually, and of course can't even remember what album it was now. And seeing another similar post this morning reminded me to ask.

What in that REGEXP tells it to cut up to "x"?

For me the example was so unspecific that I took the "x" as a placeholder for any single character enclosed by spaces followed by an uppercase character.
So it is \s.\s\u

So this was only a test for me and there was no real use case behind it?

Okaaayyyy.... I went back and dug thru the Recycle Bin, and found them. This is what the TITLES looked like:

03 - Symphonie Nr. 1 - III. Menuetto. Allegro molto e vivace
04 - Symphonie Nr. 1 - IV. Adagio. - Allegro molto e vivace
04 - Symphonie Nr. 5 - IV. Allegro. - Presto
03 - Symphonie Nr. 6 - III. Lustiges Zusammensein der Landleute
02 - Symphonie Nr. 8 - II. Allegretto scherzando
etc etc yada yada (there were about 40 total)

All I wanted was the part from the first Capital "I" on. So for example, the first one:
03 - Symphonie Nr. 1 - III. Menuetto. Allegro molto e vivace
would become
III. Menuetto. Allegro molto e vivace

I have done something similar before when the part I wanted to remove was the same in every TITLE. That was easy, and obviously, this was not that. I figured it would be a Regexp, but 10-15 minutes of playing around never worked. I did it by hand, and moved on.

But I love to learn new stuff, so I figured I would ask for the next time.

Thanks @ohrenkino for taking the time to work with me on this.

I would use the Action of Guess Values with the %title% field as the source and target %dummy% - %dummy% - %title% for these examples. No Regex required in this case.

Too easy. Thank you!

Have you tried my suggestion on the examples?
$regexp('03 - Symphonie Nr. 1 - III. Menuetto. Allegro molto e vivace',.*\s.\s(\u.*),$1)
leads to "III. Menuetto. Allegro molto e vivace"

02 - Symphonie Nr. 8 - II. Allegretto scherzando
becomes
II. Allegretto scherzando
so I would say it works.

After checking further, I amended my original suggestion to use the Action Guess Values instead of the converter. The %dummy% placeholder doesn't work in the converter.

It works here without any problems.

Edit:
Sorry. I was talking about the converter "Filename-Tag", not the converter "Tag-Tag".