Kt is a new one on me. I see Wikipedia now supports it, contradicting itself. But Debretts website says don't use it (which I suppose admits that people do).
But there are many pitfalls in calling people Lord. I'd recommend not bothering.
One big problem with Lord is that you can't use it with a Christian name, except as a courtesy title. "Lord Olivier" is fine, but "Lord Laurence Olivier" is wrong.
Another problem is that the surnames often don't match. So you get "Sir John Bourchier, Lord Berners", etc - "Lord Bourchier" would be wrong.
Likewise if a girl marries a Baron she can be Lady with her husband's titular name, but not with her maiden name, or with her married name if it doesn't match the title.
Lord also gets a bit silly with de jure Barons who were only deemed to have had the title after they were dead.
It also encourages the habit of giving a spurious Lord to every country squire who ever held a manor court in his kitchen.
The etiquette books tell you how to invite the 2nd son of a Marquess to a wedding, but their rules aren't necessarily appropriate when writing history. We don't have to be obsequious to dead people because they were rich, at the same time as describing how they were also incompetent and evil.
But we do have to distinguish generations, because it's pretty useless to say Lord Plodsbury was succeeded by Lord Plodsbury, even though it's correct.
I would say
- don't intermix the name and the peerage title, keep them separate. Normally, use one or the other. You can use both together (name first) in a heading, amd maybe once at the start of a bio.
- when stating the title, use the number, eg 2nd Baron Berners. Sometimes (eg Willoughby, Cobham) add the territory as well. When just referring to a man by his title, where there's no ambiguity, use the bare titular name "Berners" or stick Lord in front of it, but not too repetitively. Don't add anything else. Especially don't add the given name after Lord. "John, Lord Muck" is possible, but very formal and ceremonial, and just pedantic in other contexts.
- same goes for heir apparent using his father's junior title, except there's no number. Don't use the given name. We normally ignore this case except when the heir dies vp and never succeeds.
- same goes for wives and widows, again no number, except you can't use the bare surname, you have to say Lady every time.
- add rank markers (Sir, Dame, Bt, Knt, esq, gent) and post-nominals to the name not the title, and if doing so, use the given name as well. If using the surname without the given name, don't add anything else. If using the given name, add Sir or Dame if applicable, even repetitively.
- same applies to Lord and Lady as courtesy prefixes for sons and daughters, if they have to be mentioned at all. These are used with the surname, not the titular name. Always use the given name after the Lord or Lady.
- Lady for wives of knights and baronets - should be used without the given name, so more like a peerage or peer's wife. Best avoided altogether.
- it's correct to use Sir with KG or KBE or any other order of K, and with KB for Knight of the Bath. When using Sir for a knight bachelor, there's no need to add anything else.
I'm differing from Wikipedia here because they say "John Bourchier, 1st Baron Berners, KG" where I'd say "Sir John Bourchier KG, 1st Baron Berners".