Sitting with my wife watching Grantchester and this scenario develops in the show. I phrased the question as she asked me ver batim because I think it makes it more interesting. How do we (we being any demographic you'd like, but please specify) feel about execution (presumably by hanging) of pregnant women? Women in general? What was the process of execution like? Did sentencing through actual execution take long enough that it wasn't a big problem? Did we... Just wait?
I have almost no background knowledge of courts/crime/punishment/jails in 20th century England. But I love googling and reading. Would love some insight!
Executing (provably) pregnant women for the most part hasn't been a thing under English Common Law since 1387. The execution would be stayed until after she gave birth or resulted in it being commuted. The one exception to this rule was when a woman rushed to get pregnant a second time to avoid her execution, this could still result in her execution.
Also, the Sentence of Death (Expectant Mothers) Act 1931 would be in effect during 1954. A pregnant woman would be sentenced to life imprisonment with hard labor in lieu of an execution under that act during your year of choice. So, as far as your time period, no, a pregnant woman would not be executed during the pregnancy or even after.
Google suggestions: Pleading the belly (for pre-1931 stuff), Sentence of Death (Expectant Mothers) Act 1931 (for 1931 - 1998), Crime and Disorder Act 1998 (for post 1998 death penalty-related stuff)