Ros (Roos)/Wentworth Coat of Arms
The coat of arms on the North of the tower arch in St. Mary's Belchamp Walter appears to be that of marriage between the Wentworth and de Ros families.
British History on-line
The BHO listing for St. Mary's states that a coat of arms was wrongly painted in the 17th or 18th century (not very specific!). It does not say which.
Colours are off, but the bougets are of same type
The research for this was making searches for coats of arms that had three bulls heads and three water bougets.
The colours are off and the depiction of the bulls is not the same. However, seeing how some of the heraldry is subject to a lot of interpretation and speculation that is not surprising.
My guess at the moment is a Wentworth off-shoot and a de Rous coat of arms.
The Crofts coat of arms is recorded as the three bulls heads (sigil - a real or mythical animal) and the de Ros (or Roos) the water bougets.
Bordure Compony
The coat of arms has a Bordure Compony. This was noted by Peter Rushbrook in his analysis of the Herardry he observed in the church of St. Mary's, Belchamp Walter.
The significance of this is that there is a suggestion that there is a "break" in the hereditary line of the arms in the main body. The two families, presumed to be an branch of the Wentworths and possibly a de Ros, was not straight-forward.
Wentworth/Crofts
The Wentworth branch is seen as Crofts.
William le Rous - 1305 or 1310
From a writ 16 June, 3 Edw. II. Buckingham.
Exchange of land in Bedford and Essex between John de Botetourt and Maud.
Thomas Wentworth, 1st Earl of Cleveland
My theory regarding the provinance of the coat of arms and that it could be a Wentworth family arms relates to the purchase of the Belchamp Walter estate by the Raymonds from the Wentworths. Reading the Wikipedia entry for Thomas Wentworth, 1st Earl of Cleveland, it could explain the decline in the Wentworths empire.
The connection to the Ros/Rous family is not so clear. Both families seem to be associated with the area prior to The Raymonds but over a very wide time span. The de Rous family 1310 and the Wentworths 1591. THIS IS HIGHLY SPECULATIVE.