why is trump allowed to visit britain when he is a convicted felon?

he doesn't need a visa, because immigration laws don't apply to sitting heads of state, he is president, other people in high government to, called diplomatic immunity

He is wealthy. Laws don't apply.

Before he is allowed to visit Britain he has to get special permission from the British government. It would be the same thing if he wanted to visit Canada - but I think Canada would say no way Hoser.
Cheers!

Because he’s not a convicted felon. It was a kangaroo court with corrupt Democrat politicians who did not want Trump as president.

You need to learn a new word it’s called projection and the Democrats are good at projecting projection

Is he a felon, or a victim of lib lawfare ?

Yes his criminal record should have barred him, but I think he was exempted through "diplomatic immunity" and the general desire to avoid a geopolitical incident.