Hey folks, we're just one easy-sleevey step away from having a full-blown jacket on our hands! So without more ado, let's get those sleeves set in.
First step: actually assemble them. Your Richmond sleeves come in two parts – this is standard for tailored garments and allows the sleeve to be shaped more subtly to fit the natural curve of the arm. (Picture yourself standing still with your arms by your sides – you'll notice that the forearm bends slightly to the front.) Take the Upper Sleeve part and run two lines of long basting stitches between the dots. I would recommend machine basting here over hand-basting because it will probably (if your hand basting is anything like mine anyway!) enable you to pull up more frequent but smaller 'gathers' for easing. In an ideal world, you would run one line of basting within the 1.5cm (5/8 inch) seam allowance and one outside it, but this will depend on how easily your fabric retains the puncture holes of a needle – my velvet was a little sensitive to this so I kept my two lines of basting within the seam allowance. 
Gently pull on the bobbin threads to create some very gentle gathers in the sleeve head. These will help fit the sleeve head into the jacket armscye (armhole). 
With right sides together, stitch the Under Sleeve to the Upper Sleeve down each side, matching the notches so you know which side is which. Press these seams open. 
With the jacket the wrong way out, and the sleeve the right way out, insert the sleeve into the jacket armscye. You should match the top notch in the sleeve to the shoulder seam of the jacket, and match the other notches; do not try to match the sleeve seams to the bodice seams. Use the lines of basting to ease the sleeve head so that there's an even amount of excess spread between the dots, and never so much that a pucker will be created. Pin in place, and then, ideally, hand-baste. It is easy for a sleeve to slip out of place, or to catch too much fabric in your stitching, so securing it ahead of machining with some hand-basting will most likely save you a lot of hassle fixing niggles. If you baste it, you can also do a quick try-on to make sure you are happy with where your shoulder ends.
Finally, stitch the sleeve in place, starting and ending at the top, at the shoulder seam. Repeat for the second sleeve. Clip the seam allowance around the curves, and press the seam allowance in the direction of the sleeve, away from the body. With just a few steps we've leapt forwards! You might take a look at your sleeves now and think 'yay!', or you might think 'hmm, that's a bit ... flat'. If you're in the latter camp then my next blog post is for you – shoulder pads and sleeve heads! If you're in the first camp, hang on in there and by the end of the week we'll be starting on our linings! x