Re Oaths to the Barons Committee under Article 61 of Magna Carta, my advice as a founder member of the Magna Carta Society which started the activation of the Barons Committee is this. Do what the authorities that the initiative was based on specify.

Here is the authority for "Diffidatio:

“ A metrical chronicle (4) records the threat to depose the King, (John) unless he fully amended the law and furnished undoubted guarantees for a lasting peace. On 5th May, the barons went through the ceremony of diffidatio, or formal renunciation of allegiance,(1) a recognised feudal right, and not involving treason if justified by events and properly intimated to the overlord.(2)

(4) Chronica de Mailros, sub anno 1215. 1. Blackstone, Great Charter, p. xiii, citing Annals of Dunstable (p. 43), says they were absolved at Wallingford by a Canon of Durham. 2. Cf. Adams, Origin, 181 n.; 306, 312; cf. also infra under c. 61…”.

Note the words “ Properly intimated to the overlord…”. That means a sworn affidavit signed in front of a Crown Official and served on The Queen.

The complicated alternatives made up by the likes of the Common Law Court on the subject are just wrong.

If you want the protection that Article 61 gives you the presently accepted form of an affidavit is contained in the Civil Procedure Rules. There is nothing here that is inconsistent with the English common law. A copy of your affidavit should be served on the last known address of The Queen by Registered Post. If there is no satisfactory response after 10 days another affidavit stating that you have had no satisfactory response should be sent. If there is no response after 3 days the matter is closed. Keep your proofs of posting and original copies of the documents.

This is PRACTICE DIRECTION 32 – EVIDENCE:

“ AFFIDAVITS

Deponent

2 A deponent is a person who gives evidence by affidavit or affirmation.

Heading

3.1 The affidavit should be headed with the title of the proceedings (see paragraph 4 of Practice Direction 7A and paragraph 7 of Practice Direction 20); where the proceedings are between several parties with the same status it is sufficient to identify the parties as follows:

Number:

A.B. (and others) Claimants/Applicants

C.D. (and others) Defendants/Respondents

(as appropriate)

3.2 At the top right hand corner of the first page (and on the backsheet) there should be clearly written:

(1) the party on whose behalf it is made,

(2) the initials and surname of the deponent,

(3) the number of the affidavit in relation to that deponent,

(4) the identifying initials and number of each exhibit referred to, and

(5) the date sworn.

Body of affidavit

4.1 The affidavit must, if practicable, be in the deponent’s own words, the affidavit should be expressed in the first person and the deponent should:

(1) commence ‘I (full name) of (address) state on oath ……’,

(2) if giving evidence in his professional, business or other occupational capacity, give the address at which he works in (1) above, the position he holds and the name of his firm or employer,

(3) give his occupation or, if he has none, his description, and

(4) state if he is a party to the proceedings or employed by a party to the proceedings, if it be the case.

4.2 An affidavit must indicate:

(1) which of the statements in it are made from the deponent’s own knowledge and which are matters of information or belief, and

(2) the source for any matters of information or belief.

4.3 Where a deponent:

(1) refers to an exhibit or exhibits, he should state‘there is now shown to me marked ‘…’ the (description of exhibit)’, and

(2) makes more than one affidavit (to which there are exhibits) in the same proceedings, the numbering of the exhibits should run consecutively throughout and not start again with each affidavit.

Jurat

5.1 The jurat of an affidavit is a statement set out at the end of the document which authenticates the affidavit.

5.2 It must:

(1) be signed by all deponents,

(2) be completed and signed by the person before whom the affidavit was sworn whose name and qualification must be printed beneath his signature,

(3) contain the full address of the person before whom the affidavit was sworn, and

(4) follow immediately on from the text and not be put on a separate page.

Format of affidavits

6.1 An affidavit should:

(1) be produced on durable quality A4 paper with a 3.5cm margin,

(2) be fully legible and should normally be typed on one side of the paper only,

(3) where possible, be bound securely in a manner which would not hamper filing, or otherwise each page should be endorsed with the case number and should bear the initials of the deponent and of the person before whom it was sworn,

(4) have the pages numbered consecutively as a separate document (or as one of several documents contained in a file),

(5) be divided into numbered paragraphs,

(6) have all numbers, including dates, expressed in figures, and

(7) give the reference to any document or documents mentioned either in the margin or in bold text in the body of the affidavit.

6.2 It is usually convenient for an affidavit to follow the chronological sequence of events or matters dealt with; each paragraph of an affidavit should as far as possible be confined to a distinct portion of the subject.

Inability of Deponent to read or sign affidavit

7.1 Where an affidavit is sworn by a person who is unable to read or sign it, the person before whom the affidavit is sworn must certify in the jurat that:

(1) he read the affidavit to the deponent,

(2) the deponent appeared to understand it, and

(3) the deponent signed or made his mark, in his presence.

7.2 If that certificate is not included in the jurat, the affidavit may not be used in evidence unless the court is satisfied that it was read to the deponent and that he appeared to understand it. Two versions of the form of jurat with the certificate are set out at Annex 1 to this practice direction.

Alterations to affidavits

8.1 Any alteration to an affidavit must be initialled by both the deponent and the person before whom the affidavit was sworn.

8.2 An affidavit which contains an alteration that has not been initialled may be filed or used in evidence only with the permission of the court.

Who may administer oaths and take affidavits

9.1 Only the following may administer oaths and take affidavits –

(1) a commissioner for oaths6;

(2) omitted;

(3) other persons specified by statute7;

(4) certain officials of the Senior Courts8;

(5) a circuit judge or district judge9;

(6) any justice of the peace10; and

(7) certain officials of any county court appointed by the judge of that court for the purpose11.

9.2 An affidavit must be sworn before a person independent of the parties or their representatives…”.

https://www.justice.gov.uk/courts/procedure-rules/civil/rules/part32/pd_part32#affidavits

Regarding the fee for witnessing an affidavit, for solicitors it was set at £5 many years ago with £1 for each exhibit. Paying any more than that is your choice.