A mechanical seal assembly adapted for arrangement around a rotating shaft, the mechanical seal assembly having a first and a second seal ring, the first seal ring axially shiftable relative to the rotating shaft and the second seal ring axially-fixed relative to the rotating shaft, the mechanical seal assembly comprising: a biasing mechanism that urges the axially shiftable first seal ring toward the axially fixed second seal ring; an annular flexible sealing membrane comprising: a flange portion arrangeable between the axially shiftable first seal ring and the biasing mechanism, the flange portion being axially shiftable relative to the rotating shaft by forces transmitted to the flange portion by the biasing mechanism, and the first seal ring; a flexible connection portion at a radially inward extent of the flange portion, wherein the flexible connection portion presents an angular facet at a radially inward side; a coaxial portion extending axially from the flexible connection portion, the coaxial portion held axially fixed to a stub sleeve by an annular band at an outer diameter and the stub sleeve at an inner diameter, wherein the stub sleeve abuts the coaxial portion and the axially shiftable first seal ring; characterised in that the stub sleeve abuts the angular facet, and the flexible connecting portion is configured such that it flexes in response to axial movement of the axially shiftable first seal ring and the flange portion such that the closing force applied to the axially shiftable first seal ring is not affected; and such that axially inward translation of the shaft causes the flange portion to translate axially inboard and radially inward against the stub sleeve. a biasing mechanism that urges the axially shiftable first seal ring toward the axially fixed second seal ring; an annular flexible sealing membrane comprising: a flange portion arrangeable between the axially shiftable first seal ring and the biasing mechanism, the flange portion being axially shiftable relative to the rotating shaft by forces transmitted to the flange portion by the biasing mechanism, and the first seal ring; a flexible connection portion at a radially inward extent of the flange portion, wherein the flexible connection portion presents an angular facet at a radially inward side; a coaxial portion extending axially from the flexible connection portion, the coaxial portion held axially fixed to a stub sleeve by an annular band at an outer diameter and the stub sleeve at an inner diameter, wherein the stub sleeve abuts the coaxial portion and the axially shiftable first seal ring; characterised in that the stub sleeve abuts the angular facet, and the flexible connecting portion is configured such that it flexes in response to axial movement of the axially shiftable first seal ring and the flange portion such that the closing force applied to the axially shiftable first seal ring is not affected; and such that axially inward translation of the shaft causes the flange portion to translate axially inboard and radially inward against the stub sleeve. a flange portion arrangeable between the axially shiftable first seal ring and the biasing mechanism, the flange portion being axially shiftable relative to the rotating shaft by forces transmitted to the flange portion by the biasing mechanism, and the first seal ring; a flexible connection portion at a radially inward extent of the flange portion, wherein the flexible connection portion presents an angular facet at a radially inward side; a coaxial portion extending axially from the flexible connection portion, the coaxial portion held axially fixed to a stub sleeve by an annular band at an outer diameter and the stub sleeve at an inner diameter, wherein the stub sleeve abuts the coaxial portion and the axially shiftable first seal ring; characterised in that the stub sleeve abuts the angular facet, and the flexible connecting portion is configured such that it flexes in response to axial movement of the axially shiftable first seal ring and the flange portion such that the closing force applied to the axially shiftable first seal ring is not affected; and such that axially inward translation of the shaft causes the flange portion to translate axially inboard and radially inward against the stub sleeve.