Exhibit 4.12

Translation
of notarised version 11 March 2003

Today
appeared the following persons before me the undersigned Notary

|                                                                                                                                                                                                                                                                                                                                                                                                         |  |                                                                                                       |  |                    
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |  | ----------------------------------------------------------------------------------------------------- |  | -------------------
|1.                                                                                                                                                                                                                                                                                                                                                                                                       |  | Dr. Björn-Axel Dißars, lawyer (* 14 March 1967), with his offices at Warburgstrasse 50, 20354 Hamburg
|acting not on behalf of himself but pursuant to the power of attorney granted him, a certified copy of which is attached to this Agreement, on behalf of Spirent GmbH, a private limited company under the laws of Germany, registered in the commercial
register of the local court in Elmshorn under registration number HRB 1948 and with headquarters at Grosser Moorweg 45, 25436 Tornesch, Germany
|                                                                                                                                                                                                                                                                                                                                                                                                         |  |                                                                                                       |  | (the "Seller");    
|and                                                                                                                                                                                                                                                                                                                                                                                                      |  |                                                                                                      
|2.                                                                                                                                                                                                                                                                                                                                                                                                       |  | Mr. Sven-Michael Hohorst (* 05 March 1963), Artilleriestrasse 5a, 32427 Minden                       
|                                                                                                                                                                                                                                                                                                                                                                                                         |  |                                                                                                       |  | (the "Purchaser "),

The
person appearing as per 1 above identified himself by presenting his valid identification papers The person appearing as per 2 above is personally known to the Notary.

As
far as this Contract contains English language provisions, the Notary convinced himself that the person appearing are able to sufficiently understand English. The Notary stated that he is able to
sufficiently read and understand English.

The
Notary asked the persons appearing whether, unless instructed by all parties jointly, he, besides his official duty as a notary, or any other person being a member of his professional partnership
was already involved in the matter being the subject of this recording. The Parties declared that this was not the case.

The
Parties asked for recording of the following

SHARE SALE AND PURCHASE AGREEMENT

They
stated:

PREAMBLE

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THEREFORE,
the Seller and the Purchaser (collectively the "Parties") agree as follows:

Pursuant
to the terms and conditions set forth in this Agreement, the Seller and the Purchaser agree as follows:

The
Seller agrees to sell and Purchaser agrees to buy the Share.

The
Share is sold and purchased free and clear of all encumbrances, together with the right to receive all undistributed dividends in respect of previous business years and the current business year.

The
Seller hereby transfers the Share to Purchaser and Purchaser accepts such transfer.

The
transfer of the Share to the Purchaser is subject to the following conditions precedent (the "Conditions Precedent") having been satisfied.

2

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Account no.:

37859466Type of Account:

Euro AcccountBank (the "Bank"):

HSBC International DivisionLondonSort Code (BLZ):

40-05-15Swift Code:

MID LGB 11Beneficiary:

Spirent plc.




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The
Parties hereby agree that for a period of three years following the Closing Date or one year following termination of the trading relationship between WAGO Kontakttechnik GmbH on the one hand and
Spirent plc. and certain of its affiliates as perExhibit 6on the other handwhatever occurs laterthey shall not, and
shall cause their affiliates not to

in
each case without prior written consent of the respective other Party or its affiliate being the employer of such individual; provided, however, that this Section shall not prohibit soliciting the
employment of any such individual who has been terminated by the respective other Party, its affiliates, its parent company or its parent company's affiliates; and provided, further, that the
placement of advertisements in newspapers or journals of general circulation not directed or targeted at any such individuals shall not constitute solicitation for purposes of this Section.

Each
Party shall bear the cost of its own legal and other advisors incurred in connection with the negotiation, execution and completion of this Agreement and the transaction contemplated hereby as
well as any personal taxes arising therefrom. All transfer taxes, notary's and court charges in connection with the execution and completion of this Agreement shall be borne by the Purchaser.

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6

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The
recording Notary further instructed that he cannot advise on the tax consequences of this Agreement and its fulfilment. This is the duty of tax authorities or tax accountants.

The
recording was interrupted at    and started again on .

This
protocol and its exhibits were read by the Notary to the persons appearing and were accepted and signed by them as follows:

|                      |  | 
|--------------------- |  | 
|Spirent B.V.
By:      |  | 
|                      |  | 
|Dr. Björn-Axel Dißars
|                      |  | 
|Sven-Michael Hohorst 

8

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Exhibit 2.1 (c)

Waiver of Pre-emption Right and Consent to the Sale and Transfer

I
herewith waive my pre-emption right with respect to the share of € 15,300 held by Spirent GmbH in WAGO Verwaltungs-GmbH (the "Share") and consent
to the sale and transfer thereof to Mr. Sven-Michael Hohorst



| |  | 
| |  | 
| |  | 

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Exhibit 2.1 (d)

Guarantee payable on first demand

[Letterhead of Spirent plc.]

Guarantee

Spirent
GmbH, a private limited company under the laws of Germany, registered in the commercial register of the local court in Elmshorn under registration number HRB 1948 and with headquarters at
Grosser Moorweg 45, 25436 Tornesch, Germany (the "Seller");

and

Sven-Michael
Hohorst [    ] (the "Purchaser");

have
entered into an agreement for the sale and transfer of shares in WAGO Verwaltungs-GmbH (the "Agreement")

We,
Spirent plc, hereby give a guarantee ("Bürgschaft") to the Purchaser for all claims for payment that the Purchaser may have against
the Seller under the Agreement.

This
guarantee is limited to an amount of € 30,538.00.

This
guarantee is payable on the Purchaser's first written demand specifying the amount and legal cause of the Purchaser's claim against the Seller and stating that the Seller has failed to comply
with its payment obligation in respect thereof.

This
guarantee shall expire when this document is returned to us by or with the consent of the Purchaser or on 11 March 2033, whichever occurs earlier, unless a demand for payment
hereunder, complying with the provisions of the preceding paragraph, has been received by us on or before that date.

This
document shall be returned to us immediately upon expiry of our guarantee.

Any
rights or obligation arising out of this guarantee may only be transferred to a third party with our prior written consent. We hereby explicitly and irrevocably agree to a transfer of rights
hereunder to Dresdner Bank AG.

This
guarantee shall be subject to German law. Any disputes arising out of or in connection with this guarantee shall be settled by arbitration in accordance with the UNCITRAL Arbitration Rules in
effect on the date hereof. The appointing authority shall be the President of the Hamburg Court of Appeals (Präsident des Oberlandesgerichts in
Hamburg). The number of arbitrators shall be three. The place of arbitration shall be Hamburg. The language that may be used in the arbitral proceedings shall be German or
English.

In
the event that any provision of this guarantee should be ineffective, this shall not affect the validity of the remainder hereof.

This
guarantee is subject to and shall be governed in accordance with German law.

|             |  |             
|------------ |  | ------------
|[...], [...] |  |             
|             |  |             
|             |  | Spirent plc.
|             |  | by:         

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Exhibit 6

List of Affiliates

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