Whittlesey on Wikipedia.
 

The Baptist Church (2023 Streetview) is on Gracious Street. It's dated to 1836 on the church website history page. The 25" O.S. map of 1901 labels it as Zion Chapel. TL 2687 9737. The same map also shows a Baptist Chapel on Windmill Street at TL 2675 9732. It survived in use until the mid-20th century at least, but has since been demolished, and replaced by housing, which has been there since at least 2009 (Streetview).

Kingdom Hall of Jehovah's Witnesses on Church Street. It stands on, or very close to, the site of a Meth. Chapel (Free Wes.) marked on a map of 1901. TL 2674 9717. © Tony Preston.

A Methodist/U.R.C. Church (2021 Streetview) stands on Queen Street. It, or a predecessor chapel, is marked on a map of 1901 as Chapel, but is otherwise unidentified, but is likely to have been Methodist originally (see following comments). TL 2697 9719. Link. Similarly, the likely predecessor of the U.R.C. is marked as a Congregational Chapel on Broad Street at TL 2681 9716. It survives as Whittlesey Christian Church.

The cemetery on Cemetery Road has a Mortuary Chapel. Vegetation interferes with most Streetviews, but one from 2019 shows most of the chapel. TL 2739 9727. A tomb in the cemetery is listed as grade II.

A Primitive Methodist Chapel shows on a map of 1901 on Woolpack Lane, at TL 2681 9696. Seen by Streetview in 2022, the tablet above the porch reads "Masonic Hall", though it now appears to be disused.

St. Andrew on Church Street. TL 2668 9692. © John Balaam (2002). Another view, and the altar, both © Chris Stafford (2013). Another view, © Tony Preston. Link. Grade II* listed.

St. Jude the Apostle (R.C.) on Station Road and Scaldgate, as seen by Streetview in 2022. TL 2713 9690. Link.

St. Mary on Station Road. TL 2701 9695. © Tony Preston. Previously in the "Unknown" section, this interior view of St. Mary was identified by Phil Draper and Simon Davies. Original entry follows - "Judy Flynn has an old postcard of a church interior, and labelled as "St. Mary, W'sea". It was bought understanding that it was in Yorkshire, but has been unable to find a likely candidate". Link. Grade I listed.

The Salvation Army Church (2021 Streetview) is on Church Street and Duddington Gardens. TL 2671 9713.