This is the time of year when theatrical producers start angling for the office party and Christmas outings crowds, and two likely contenders have just opened in London.Like the long-running Billy Elliot, Made in Dagenham is adapted from a successful British movie and concerns an industrial dispute; where Billy Elliot musicalised the 1984 miners’ strike, this show spins song-and-dance drama from the stand-off at the Ford car plant in Dagenham in 1968, when the women who stitched the seats walked out for equal pay with the men who handled the chassis.The drawback of this material for musical adaptation is that because it is based on actual events – some of the original women joined the first night curtain-call – the level of emotional incident is limited to average domest