Westerman took his league goals tally to 16 but, more importantly, Whitchurch became the first Welsh side to qualify for the PizzaExpress National League play-offs.
In the South, Anchorians secured the draw they needed at Fareham to finish second to Hampstead and Westminster in the Nastro Azzurro Premier and take the second South place in the play-offs.
Crostyx had two useful wins over the weekend to go into pole position in the Norwich Union East Premier and now look favourites to take the last play-off place.
With Ipswich winning 2-0 at Stevenage on Saturday - goals from Andy Cook and Matt Day - they held on to the lead overnight after Crostyx kept in the race with a 3-0 home victory against Colchester. Andy Macleod, Paul Morris and Nick Duck scored the goals.
On Sunday, Paul Dover converted three penalty strokes in Crostyx's 3-1 win at Norwich in a rearranged fixture. Croystx now go into next Saturday's final game at home to Blueharts two points ahead of Ipswich, who entertain Pelicans.
Denise Shorney scored a hat-trick for Reading in their 8-1 win against Cheam as the Berkshire club won the South Women's League, becoming the first women's play-off qualifier.
INTER-LEAGUE PLAY-OFFS: Pool A: Ipswich or Crostyx; Olton and West Warwick; Hampstead & Westminster and Harborne. Pool B: Formby, Whitchurch, Anchorians and Doncaster. (Ties to be played on 26 and 27 March at Olton).
HA MEN'S TROPHY Semi-final draw: Ashford v Blackheath; Bowdon v Barnes. (Ties to be played on Sunday, 20 March).Reuse content