The FOOT and STRUT lexical sets did not undergo a historical split in the North of England, and these vowels are said to remain a single phoneme for present day Northern English speakers. However, several sources report variation in this respect. We analyse this variation in production, using acoustic analysis of crowdsourced data from 141 speakers of seven Northern English urban dialects. 36 speakers in our sample show a categorical distinction between FOOT and STRUT. Highly mobile speakers are more likely to have this distinction, compared to speakers with low mobility. A categorical split is also more likely in speakers from Newcastle, compared to several other cities. While we find no evidence that FOOT and STRUT vowels are splitting in the North, we discuss how the observed variation may contribute to the presence of marginal contrasts.