After months of searching, I've finally located the Sarum Rite Sequence for use at the traditional EF Votive Mass "Recordare" for use in time of pestilence.

Does anyone know of the original music for this? I assume it could be used as a Motet at Mass during this pandemic.

It is given, in Latin with a poetic English translation, on pages 261-266 in Appendix D of 'Musica sanat corpus per animam': Toward Understanding of the Use of Music in Response to Plague, 1350-1600, the doctoral thesis of Christopher Brian Macklin. He provides his sources as follows:

Dickinson, Francisci Henrici, ed. Missale Ad Usum Insignis Et Praeclare Ecclesie Sarum. 4 vols. Vol. 2. (Comune Sanctorum). London & Oxford: J. Parker & Soc., 1867, cols. 886*-890*.
The translation of the sequence is adapted from The Sarum Missal in English, trans. Frederick E. Warren. 2 vols. Vol. 2. London: A. R. Mowbray & Co., 1913, p. 203-06.

I have divided it into three parts – a prayer to the Lord for deliverance; a list of Old Testament exemplars of penitence and intercession; and an appeal to Our Lady for her aid – and numbered the verses.

In order to shorten this rather long text to make its use more practical, I have placed asterisks before those verses that are not ad rem and can be omitted.

The Latin is given first, then the English:

Sequentia. (Miss. Sar.)
[I.]
*1a. Jubilemus pia mente,
voci corde concinente,
Trinitate collaudantes;

*1b. Patrem Prolemque precemur,
Sanctum Pneuma veneremur,
laudis melos concrepantes.

2a. Omnes una proclamemus,
summum Deum imploremus,
misereri ut dignetur;

2b. cor gravatur, mens languescit,
jam gens mœret et plangescit,
pestis morsum dum veretur.

3a. Aura lædit, furit pestis,
morbus urit, nulla mœstis
spes salutis redditur;

3b. mare fluit mixtum felle,
jam tempestas, jam procellæ,
plebs ubique premitur.

4a. Si pro malis irascaris,
tempus est ut revertaris;
pie Jesu, miserere;

4b. leo lustrans, oves quærit;
nisi præsis, ovis perit;
bone pastor, nos tuere.

*5a. Terra, mare, firmamenta,
quæque parent elementa,
tuo facta numine;

*5b. mare novit te calcantem,
dum te sentit ambulantem,
factor fertur flumine.

*6a. Cuncta sistunt, te jubente;
Non moventur, sed repente
Redduntur pacifica;

*6b. Toto nisu, tota cura,
Omnis laudat te factura,
O virtus almifica.

7. Auras mitte nobis lætas,
pestes prece procul pelle,
transfer nos ad vitæ metas,
ne nos turbent tot procellæ.

8. Olim culpa nos ligati
Respirantes cedimus,
Corde mœsto flagellati,
tibi soli credimus.

[*II.]
*9. Lex antiqua transgressores
Conversos eripuit;
tuæ legis abusores
pie dum corripuit.

*10a. Joab Abner persequente,
et hunc armis insequente,
prece datur venia;

*10b. Joab vitam consecutus,
nocte viam transit tutus,
per montis cacumina.

*11a. Davidi prophetico
Vita datur termino,
pro delicto gravi;

*11b. tersum fugit facinus,
dum fatetur vocibus,
inquiens, Peccavi.

*12a. Ezechias reddit fletum,
et peccatum est deletum,
statim ut pœnituit;

*12b. fletum fecit et profecit,
sibi Deus hinc adjecit
annos et constituit.

*13a. Mitis Hester piæ mentis
Pro salute suæ gentis,
Assuerum adiit;

*13b. hinc fit salus Mardochæo,
cur æquatur Aman reo,
qui suspensus periit.

*14. Virtus Judith de supernis
Diva dum illuminat,
Caput aufert Holofernis
Et captivos liberat.

[III.]
*15. Mater ergo summi regis,
tibi natus Christus verus,
Vos signavit umbra legis,
Hester tu, Hic Assuerus.

16. Virgo Natum intercede,
ut afflictos liberet;
salvet hos a pestis cæde,
quos pie redemerat.

17a. Virgo mater, maris stella,
Fons hortorum, Verbi cella,
ne nos pestis aut procella
peccatores obruant.

17b. Eja, mater, terge fletum,
tempestatis tolle fretum,
cor mœstorum redde lætum,
jam preces subveniant.

18a. Proles parcit si peroras,
mater ergo rumpe moras;
posce tuum Filium;

18b. aura fœda rumpens pestis
simul cadant, confer mœstis
salutis auxilium.

19a. Nostros tuus ipse Natus
Tollat pœnas es reatus,
nobis præstans consolamen,

19b. Sui regni sempiterni,
ubi cives sunt superni,
personemus omnes, Amen.

******

Sequence.
[I.]
*1a. With pious minds let us rejoice,
our hearts responding to our voice,
the Trinity to praise;

*1b. The Father and the Son entreat,
and Holy Ghost with reverence meet,
while lauding hymns we raise.

2a. To him [> God] together let us cry,
beseeching of the Lord on high
that he will pitying hear:

2b. Our hearts are faint, our souls oppressed,
the nation now is sore distressed,
the plague strikes all with fear.

3a. Fierce pestilence doth taint the air,
disease prevails, and none doth dare
to hope for safety more;

3b. The waves with poison mingled flow,
and storms and tempests wildly blow;
the people mourn full sore.

4a. If thou dost for our sins chastise,
now it is time thou should'st arise –
have mercy, Jesu kind:

4b. The lion seeks the flock to tear;
good Shepherd, if thou art not there
no succour can we find.

*5a. The earth, the sea, the firmament,
and each obedient element,
thy hand divine declare:

*5b. As thou didst walk the sea confessed,
thy footsteps on her waters pressed;
the floods their Maker bare.

*6a. At thy command all tumults cease,
and in a moment there is peace,
nought moves, and all is still;

*6b. All rests on thee, all reverence pays,
the whole creation thee doth praise,
O power of kindly will.

7. Send us propitious gales, we pray,
and bear us to the goal of life;
the pestilence drive far away,
and rid us of the tempest's strife.

8. We that were long time bound by sin,
turn back to thee, regaining strength;
chastised, and sad of heart within,
in thee alone we trust at length.

[*II.]
*9. Converted sinners the old law
ne'er to receive refused;
and mercifully did chastise
those who its grace abused.

*10a. As Joab after Abner went,
pursuing him with fierce intent,
good words for peace prevailed;

*10b. In safety o'er the mountain height
Joab, returning, marched by night,
else life for all had failed.

*11a. According to the appointed word,
pardon the prophet doth accord
to David's great offence;

*11b. His grievous crime is cleansed away,
when "I have sinned," he doth say,
in tones of penitence.

*12a. King Hezekiah sore doth weep;
forthwith at his repentance deep,
his sin is put aside;

*12b. He weeps, and profits by his tears,
for God doth add unto his years
a longer term beside.

*13a. The gentle Esther seeks relief
of Assuerus in her grief,
her nation's life to win;

*13b. Hence Mordecai deliverance found:
on his own gallows, Haman bound,
doth expiate his sin.

*14. Whilst heavenly valour from on high
Judith illuminates,
headless she leaves her enemy,
and captives liberates.

[III.]
*15. Thee, mother of the highest king,
the true Anointed One[,] we see,
you both the law prefiguring,
thou Esther, Assuerus he.

16. O blessed virgin, intercede,
us from the pestilence to save;
those whom thy Son redeemed and freed,
let him deliver from the grave.

17a. O virgin mother, the Word's cell,
star of the sea, thou garden-well,
the pestilential storm dispel;
let us poor sinners live;

17b. O mother, wipe our tears away,
the raging tempest still this day,
now in our trouble for us pray,
our drooping hearts revive.

18a. The Son doth spare if thou dost pray,
O mother, then, no more delay,
thy holy Child implore;

18b. Let the fell plague, the deadly blast,
together cease, and now at last
health to our land restore.

19a. Our guilt and punishment, we pray,
let thy Son wholly take away,
and us with comfort greet;

19b. And grant us of his realm a share
whose citizens eternal are:
let all "Amen" repeat.