Bath Lane is effectively a spur of East Street, down to the quay and the amenities which lay at the bottom.
William Deane, who lived in Fairfield House on East Street, gave some of his land as a gift to the people of Fareham, which is what is now known as Bath Lane recreation ground.
For years this was Fareham's only park, and it was used by the community for various events and exercises, and it also meant that this road was originally called Park Lane.
In 1838, a bathing house was built at the end of the road, using water from the creek, allowing men and women to bathe separately. As a result, the road became known as Bathing House Lane, which was later adopted as its formal name, although maps don't seem to have reflected this.
At the start of the 20th Century, the bathing house closed (to become cottages), so the street name was shortened to Bath Lane. Swimming in the creek continued to be a popular pastime until the mid-1950s, where the silting up and pollution (it was never clean by today's standards, but discarded German submarines apparently made it worse) put an end to it for most people.
The earliest map I've seen shows it as a tree-lined road, with a single property at Yewtree Cottage immediately south of the railway line. Some of the park is marked as allotments, with Payne's College by the waterfront and a well by the quay. By the end of the century, most of the trees appear to have gone, and there are a couple more properties at the top of the road, although the junction with East Street is still marked as woodland.
By 1909 Deanes Park Road was built, named in honour of William Deane and his gift (grammatical enthusiasts will be keen to know it was once apostrophised, but that appears to have been dropped with time). It was a cul-de-sac down to the recently-built sewage outlet by the waterfront. Only the six houses at the far end of the road were built at this point (those being the six red-brick terraces which are still there today), the rest of it was still fields.
Two more properties had been built on the now-renamed Bath Lane by the new junction, and the Bath Lane Cottages appear on this map next to the Quay. The cricket pavilion is shown for the first time too. Bridgefoot Terrace at the end was built in 1911.
The next map is dated 1932 and shows at least eight new properties on the west side, north of the railway. Most of the houses on Deanes Park Road are now shown, and Yewtree Cottage and the land south of it have been divided up to become more houses.
By 1953, the space on the east side (north of the railway) had all been filled by houses, replacing the development which was already there. The woodland at the East Street junction had been replaced by buildings and the housing on the south side of Deanes Park Road now extended to the esplanade.
When Eastern Way opened in 1971, Bath Lane was severed, and alternative access was required. Since land was being reclaimed anyway at the Delme Roundabout, Deanes Park Road was extended on to the creek and through the railway arches to meet the new road, replacing the track known as Esplanade. About eight properties were taken to build the road and the subway, breaking the street into Lower and Upper Bath Lane.
This is broadly how it would stay until the start of the 21st Century, when the retired gas works became Earl Godwin Close.