Good afternoon ladies and gentlemen,
I have a picture here from the engineers from the Olympic in 1911.
The full dress uniform seen on the picture here was only obligatory for the chief end senior engineers, but it seems as though all had purchased this prestigious uniform on the picture. The white trousers were officially not foreseen with full dress. Of the 27 men on the picture 14 were transferred to the Titanic. These are the following men who are numbered on the picture.
1 Junior fifth engineer William Dickson Mackie
2 Senior fifth engineer Frank Alfred Parsons
3 Chief electrician Peter Porter Sloan
4 Assistant electrician Boykett Herbert Jupe
5 Junior assistant third engineer Francis Ernest George Coy
6 Senior assistant second engineer Bertie Wilson
7 Senior fourth engineer Leonard Hodgkinson
8 Junior fourth engineer Arthur Ward
9 Junior assistant second engineer Jonathan Sheppard
10 Junior assistant second engineer Herbert Gifford Harvey
11Senior assistant fourth engineer Henry Ryland Dyer
12 Extra fifth engineer Robert Millar
13 Second engineer john Henry Hesketh
14 Senior third engineer George Fox Hosking
The descriptions of the uniform are the following
All uniform items identical to the uniform of the captain, but with no gold circle rank insignia. Cap with leather peak, without embroidery.
All uniform items identical to chief engineer except three rows gold lace.
All uniform items identical to chief engineer except two rows gold lace.
Fourth engineer and all assistant engineers
All uniform items identical to chief engineer except one row gold lace.
Fifth and Sixth engineer, boilermaker
All uniform items identical to chief engineer except cuffs without gold lace.
All uniforms items identical to the uniform of the fifth and sixth engineer. Title worked in gilt wire on both sides of the collar on full dress coat and undress.
Keep in mind this descriptions are only for the full-dress it is believed that they would be dressed in dungarees and denim shirts most of the time.
I hope this clarifies the question somewhat.