London: the step-by-step guide Michael Leapman takes a springtime walk on Turkey Street

this springtime walk on the northern edge of London takes in two splendid gardens and gives a surprising view of a famous City landmark, designed by Sir Christopher Wren but now festering in the countryside.

From the station approach, turn right up Turkey Street and take the underpass under the A10. Continue on Turkey Street for a few yards, turn right into Bowles Lane and right again at Capel Road. Turn left into Bullsmoor Lane, passing Capel Manor, a Mecca for gardeners (open 10am-4.30pm; 5.30pm at weekends).

From the garden, continue along Bullsmoor Lane and turn right into Bull's Cross, opposite the Pied Bull. Follow the road as it curves left, then turn right up Bulls Cross Ride, carried by a bridge over the M25. Just beyond the bridge, turn right down stone steps and cross a drive into a fenced path that gradually veers from the motorway until it meets the man-made New River, cut in 1613 to bring Hertfordshire water to thirsty Londoners.

Cross the river bridge and turn left up the right-hand bank, with good open views to your right as coots and mallards glide by on the water. The path swings right, around a small island, before crossing a road through aluminium kissing gates, then passing under a road bridge. Just beyond this, cross the river on a wooden footbridge. At this point the route crosses part of the grounds of the former Theobalds Palace, where James I used to enjoy hunting. On a frosty day in 1622 his horse slipped and pitched his royal rider inelegantly into the New River.

Across the footbridge, follow the footpath sign through an iron kissing gate. Cross the field diagonally to a stile beneath a blackthorn bush, leading to a footpath through a wood. Stick to the main path, with a field of young wheat on your right.

The path reaches a clearing and begins to turn away from the road ahead. As it does so, turn left and make for the road, going through a broken fence to reach it. Cross the road and head down a clear but unmarked and slightly muddy path immediately opposite, with woods on the left and a rape field on the right.

After a few hundred yards, you suddenly see, on your left, a dilapidated archway surrounded by a fence. This is Temple Bar, designed by Wren in 1672 to separate Fleet Street from the Strand. For more than 200 years it was the official western entrance to the City of London, until it was demolished in 1878 because it impeded traffic.

Ten years later the pieces were given to the brewer, Sir Henry Meux, who had the arch reconstructed here at his Cheshunt estate, where it is today sadly neglected. From time to time there are moves to have it restored and placed somewhere more appropriate, but they have so far come to nothing.

After inspecting the monument keep straight ahead, leaving it to your left, passing the red brick Gardener's Cottage and turning left onto the road. On the left you pass the farm college, with its stately brick gates, where you bear right, keeping to the main roadway, and soon reach the bridge where you first crossed the motorway.

Cross it again, and on the other side go down some rough earth steps on the left to a stile, crossing a paddock to another stile and then turning right down a lane. This leads back to Bulls Cross. Go past the Pied Bull and, after some 300 yards, you will see on your right the entrance to Myddleton House.

This was named after Hugh Myddleton, the brains behind the New River, who lived in an earlier house on the site. A more recent resident was E A Bowles (1865-1954), a noted garden writer and plantsman. He lived here all his life and the delightful garden is being restored to what it was before he died. He loved irises, and although they were not in flower when I visited the garden, they should be ready now. It is open weekdays from 10am-3.30pm and on the last Sunday in non-winter months - including this coming Sunday, from 2-5pm.

From the garden turn right down Bulls Cross. After crossing a bridge, turn left outside Forty Hill Parish Hall on to a metalled footpath. Stick to the path, which crosses the New River again, then goes over the A10. Keep on behind the houses and, just after passing under a railway bridge, turn left to get back to the station.